Hyaluronan Production Regulates Metabolic and Cancer Stem-like Properties of Breast Cancer Cells via Hexosamine Biosynthetic Pathway-coupled HIF-1 Signaling

Revealing the Role of Beesioside O from Actaea vaginata for the Treatment of Breast Cancer Using Network Pharmacology, Molecular Docking, and Molecular Dynamics Simulation

Breast cancer remains a leading cause of malignancy-related mortality among women, with rising global incidence. While surgical intervention is effective for early-stage breast cancer, drug therapy is indispensable, particularly for triple-negative breast cancer, where treatment options are still limited. Actaea vaginata, a traditional Chinese medicinal herb, has been historically applied for inflammatory conditions, including pharyngitis and stomatitis. However, its antitumor potential remains under-reported. In this study, a cycloartane triterpene saponin, beesioside O (BO), was isolated from this plant. Its antitumor activity was evaluated in vitro. Its potential therapeutic mechanisms were elucidated through network pharmacology. BO exhibited substantial potency in inhibiting breast cancer cells. Network pharmacology analysis uncovered 179 potential pharmacological targets of BO, which were predominantly concentrated in pathways, such as pathways in cancer, the PI3K-Akt signaling pathway, and chemical carcinogenesis receptor activation. Molecular docking analysis indicated that STAT3 exhibited minimal binding energy with BO. Additionally, molecular dynamics simulations verified the conformational stability of the BO-STAT3 complex. Western blot analysis demonstrated that STAT3 was downregulated following administration. These results imply that BO may exhibit a multi-target, synergistic therapeutic effect against breast cancer, with STAT3 recognized as a pivotal target. This study demonstrates the potential of BO for development as a chemotherapeutic agent for breast cancer treatment. It lays the groundwork for further exploration of BO's bioactivity and provides valuable insights into its molecular mechanisms in breast cancer therapy.

Hyaluronic acid promotes hepatocellular carcinoma proliferation by upregulating CD44 expression and enhancing glucose metabolism flux

Hepatocellular carcinoma (HCC), known for its high malignancy, exhibits a critical feature in its progression through the alteration of metabolic pathways. Our study initially observed an increase in hyaluronic acid (HA) secretion by HCC cells through ELISA analysis. Further protein-protein interaction (PPI) network analysis highlighted CD44 and HAS2 as critical nodes, suggesting their pivotal roles in HA metabolism. Silencing of HAS2 markedly reduced HA production and suppressed cell proliferation, whereas overexpression of HAS2 enhanced HA synthesis and promoted cellular growth. Moreover, we found that HA, through binding to CD44, activates the downstream PI3K/AKT/MYC signaling pathway. This activation not only upregulates MYC expression but also leads to an increase in GLUT1 expression level. As a transcription factor for GLUT1, MYC directly facilitates its expression, thereby enhancing glucose uptake and glycolytic activity. Additionally, CD44 can directly interact with GLUT1, further promoting glucose flux. These mechanisms collectively boost anaerobic glycolysis and the hexosamine biosynthetic pathway (HBP), providing essential energy and metabolites for rapid liver cell proliferation. Our findings not only elucidate the central role of HA in regulating cellular metabolism but also lay a solid theoretical foundation for developing therapeutic strategies targeting HA-related metabolic pathways.

Extracellular matrix shapes cancer stem cell behavior in breast cancer: a mini review

Today, cancer has become one of the leading global tragedies. It occurs when a small number of cells in the body mutate, causing some of them to evade the body's immune system and proliferate uncontrollably. Even more irritating is the fact that patients with cancers frequently relapse after conventional chemotherapy and radiotherapy, leading to additional suffering. Scientists thereby presume that cancer stem cells (CSCs) are the underlying cause of metastasis and recurrence. In recent years, it was shown that not only can chemotherapy and radiotherapy underperform in the treatment of breast cancer, but they can also increase the number of breast cancer stem cells (BCSCs) that transform regular breast cancer cells into their own population. Such data somewhat support the aforementioned hypothesis. Meanwhile, our understanding of the extracellular matrix (ECM) has changed considerably over the last decade. A lot of studies have bit by bit complemented human knowledge regarding how the ECM greatly shapes the behaviors of BCSCs. In this review, we highlighted the influence on BCSCs exerted by different critical components and biochemical properties of ECM.

Network-Based Bioinformatics Highlights Broad Importance of Human Milk Hyaluronan

Human milk (HM) is rich in bioactive factors promoting postnatal small intestinal development and maturation of the microbiome. HM is also protective against necrotizing enterocolitis (NEC), a devastating inflammatory condition predominantly affecting preterm infants. The HM glycosaminoglycan, hyaluronan (HA), is present at high levels in colostrum and early milk. Our group has demonstrated that HA with a molecular weight of 35 kDa (HA35) promotes maturation of the murine neonatal intestine and protects against two distinct models of NEC. However, the molecular mechanisms underpinning HA35-induced changes in the developing ileum are unclear. CD-1 mouse pups were treated with HA35 or vehicle control daily, from P7 to P14, and we used network and functional analyses of bulk RNA-seq ileal transcriptomes to further characterize molecular mechanisms through which HA35 likely influences intestinal maturation. HA35-treated pups separated well by principal component analysis, and cell deconvolution revealed increases in stromal, Paneth, and mature enterocyte and progenitor cells in HA35-treated pups. Gene set enrichment and pathway analyses demonstrated upregulation in key processes related to antioxidant and growth pathways, such as nuclear factor erythroid 2-related factor-mediated oxidative stress response, hypoxia inducible factor-1 alpha, mechanistic target of rapamycin, and downregulation of apoptotic signaling. Collectively, pro-growth and differentiation signals induced by HA35 may present novel mechanisms by which this HM bioactive factor may protect against NEC.

Injectable PEG Hydrogels with Tissue-Like Viscoelasticity Formed through Reversible Alendronate-Calcium Phosphate Crosslinking for Cell-Material Interactions

Synthetic hydrogels provide controllable 3D environments, which can be used to study fundamental biological phenomena. The growing body of evidence that cell behavior depends upon hydrogel stress relaxation creates a high demand for hydrogels with tissue-like viscoelastic properties. Here, a unique platform of synthetic polyethylene glycol (PEG) hydrogels in which star-shaped PEG molecules are conjugated with alendronate and/or RGD peptides, attaining modifiable degradability as well as flexible cell adhesion, is created. Novel reversible ionic interactions between alendronate and calcium phosphate nanoparticles, leading to versatile viscoelastic properties with varying initial elastic modulus and stress relaxation time, are identified. This new crosslinking mechanism provides shear-thinning properties resulting in differential cellular responses between cancer cells and stem cells. The novel hydrogel system is an improved design to the other ionic crosslink platforms and opens new avenues for the development of pathologically relevant cancer models, as well as minimally invasive approaches for cell delivery for potential regenerative therapies.

GFPT1 accelerates immune escape in breast cancer by modifying PD-L1 via O-glycosylation

BACKGROUND

Immune escape is one of the causes of poor prognosis in breast cancer (BC). Glutamine-fructose-6-phosphate transaminase 1 (GFPT1) is the first speed-limiting enzyme of the hexosamine biosynthesis pathway (HBP) and is essential for the progression of BC. Nevertheless, the mechanism of the influence of GFPT1 in BC immune escape is not clear.

METHODS

First, the level of GFPT1 in BC was analyzed by starbase, and GFPT1 expression in BC tissues was measured by qRT-PCR, western blot and IHC. Then, the O-GlcNAc levels were detected by western blot. Thereafter, Co-IP was applied to examine the relationship between GFPT1 and PD-L1. At last, a mouse model was constructed for validation in vivo.

RESULTS

Firstly, we discovered that GFPT1 was obviously strengthened in BC. Knockdown or introduction of GFPT1 correspondingly degraded and elevated O-GlcNAc levels in cells. Further researches revealed that there was a reciprocal relationship between GFPT1 and PD-L1. Mechanistically, we disclosed that GFPT1 enhanced PD-L1 protein stability through O-glycosylation. More interestingly, GFPT1 accelerated BC cell immune escape via upregulation of O-glycosylation-modified PD-L1. In vivo, silencing of GFPT1 attenuated immune escape of BC cells by reducing PD-L1 levels.

CONCLUSION

GFPT1 promoted BC progression and immune escape via O-glycosylation-modified PD-L1. GFPT1 may be a potential target for BC therapy.

Deciphering Drug Resistance: Investigating the Emerging Role of Hyaluronan Metabolism and Signaling and Tumor Extracellular Matrix in Cancer Chemotherapy

Hyaluronan (HA) has gained significant attention in cancer research for its role in modulating chemoresistance. This review aims to elucidate the mechanisms by which HA contributes to chemoresistance, focusing on its interactions within the tumor microenvironment. HA is abundantly present in the extracellular matrix (ECM) and binds to cell-surface receptors such as CD44 and RHAMM. These interactions activate various signaling pathways, including PI3K/Akt, MAPK, and NF-κB, which are implicated in cell survival, proliferation, and drug resistance. HA also influences the physical properties of the tumor stroma, enhancing its density and reducing drug penetration. Additionally, HA-mediated signaling contributes to the epithelial-mesenchymal transition (EMT), a process associated with increased metastatic potential and resistance to apoptosis. Emerging therapeutic strategies aim to counteract HA-induced chemoresistance by targeting HA synthesis, degradation, metabolism, or its binding to CD44. This review underscores the complexity of HA's role in chemoresistance and highlights the potential for HA-targeted therapies to improve the efficacy of conventional chemotherapeutics.

Breast cancer therapy: from the perspective of glucose metabolism and glycosylation

Breast cancer is a leading cause of mortality and the most prevalent form of malignant tumor among women worldwide. Breast cancer cells exhibit an elevated glycolysis and altered glucose metabolism. Moreover, these cells display abnormal glycosylation patterns, influencing invasion, proliferation, metastasis, and drug resistance. Consequently, targeting glycolysis and mitigating abnormal glycosylation represent key therapeutic strategies for breast cancer. This review underscores the importance of protein glycosylation and glucose metabolism alterations in breast cancer. The current research efforts in developing effective interventions targeting glycolysis and glycosylation are further discussed.

Crosstalk between T lymphocyte and extracellular matrix in tumor microenvironment

The extracellular matrix (ECM) is a complex three-dimensional structure composed of proteins, glycans, and proteoglycans, constituting a critical component of the tumor microenvironment. Complex interactions among immune cells, extracellular matrix, and tumor cells promote tumor development and metastasis, consequently influencing therapeutic efficacy. Hence, elucidating these interaction mechanisms is pivotal for precision cancer therapy. T lymphocytes are an important component of the immune system, exerting direct anti-tumor effects by attacking tumor cells or releasing lymphokines to enhance immune effects. The ECM significantly influences T cells function and infiltration within the tumor microenvironment, thereby impacting the behavior and biological characteristics of tumor cells. T cells are involved in regulating the synthesis, degradation, and remodeling of the extracellular matrix through the secretion of cytokines and enzymes. As a result, it affects the proliferation and invasive ability of tumor cells as well as the efficacy of immunotherapy. This review discusses the mechanisms underlying T lymphocyte-ECM interactions in the tumor immune microenvironment and their potential application in immunotherapy. It provides novel insights for the development of innovative tumor therapeutic strategies and drug.

Tolerable glycometabolic stress boosts cancer cell resilience through altered N-glycosylation and Notch signaling activation

Chronic metabolic stress paradoxically elicits pro-tumorigenic signals that facilitate cancer stem cell (CSC) development. Therefore, elucidating the metabolic sensing and signaling mechanisms governing cancer cell stemness can provide insights into ameliorating cancer relapse and therapeutic resistance. Here, we provide convincing evidence that chronic metabolic stress triggered by hyaluronan production augments CSC-like traits and chemoresistance by partially impairing nucleotide sugar metabolism, dolichol lipid-linked oligosaccharide (LLO) biosynthesis and N-glycan assembly. Notably, preconditioning with either low-dose tunicamycin or 2-deoxy-D-glucose, which partially interferes with LLO biosynthesis, reproduced the promoting effects of hyaluronan production on CSCs. Multi-omics revealed characteristic changes in N-glycan profiles and Notch signaling activation in cancer cells exposed to mild glycometabolic stress. Restoration of N-glycan assembly with glucosamine and mannose supplementation and Notch signaling blockade attenuated CSC-like properties and further enhanced the therapeutic efficacy of cisplatin. Therefore, our findings uncover a novel mechanism by which tolerable glycometabolic stress boosts cancer cell resilience through altered N-glycosylation and Notch signaling activation.

Aberrantly expressed HIF-1α enhances HCC stem cell-like traits via Wnt/β-catenin signaling activation after insufficient radiofrequency ablation

BACKGROUND

Radiofrequency ablation has become a favorable treatment modality for small hepatocellular carcinoma (HCC) recently; however, insufficient radiofrequency ablation (RFA) was shown to lead to enhanced invasiveness and metastasis of HCC in our previous study, while the underlying molecular mechanism has not been understood.

MATERIALS AND METHODS

In order to explore the influence of the hypoxic microenvironment on residual cancer and cancer stem cell (CSC)-like characteristics of HCC cells in this process, an in vitro hypoxic model and an insufficient RFA mouse model were established with HCC cancer cell lines. Immunochemistry staining and western blot were used to examine the expression of hypoxia-inducible factor (HIF)-1α and liver CSC markers. The 3D colon formation assay, tumor cell invasion assay, and gene transfection assays were applied to test the change in liver CSC stemness and HCC cell invasion.

RESULTS

After insufficient RFA treatment, the upregulated HIF-1α expression was associated with an increase in the CSC-like population in residual cancer. In vitro, hypoxic tumor cells showed aggressive CSC-like properties and phenotypes. Wnt/β-catenin signaling activation was shown to be necessary for the acquisition of liver CSC-like characteristics under hypoxic conditions.

CONCLUSION

Overall, the aberrantly enhanced HIF-1α expression enhanced the liver CSC-like traits via abnormal Wnt/β-catenin signaling activation after insufficient RFA, and the overexpressed HIF-1α would be a vital factor and useful biomarker during the HCC recurrence and metastasis.

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.

Fetal Reprogramming of Nutrient Surplus Signaling, O-GlcNAcylation, and the Evolution of CKD

ABSTRACT

Fetal kidney development is characterized by increased uptake of glucose, ATP production by glycolysis, and upregulation of mammalian target of rapamycin (mTOR) and hypoxia-inducible factor-1 alpha (HIF-1 α ), which (acting in concert) promote nephrogenesis in a hypoxic low-tubular-workload environment. By contrast, the healthy adult kidney is characterized by upregulation of sirtuin-1 and adenosine monophosphate-activated protein kinase, which enhances ATP production through fatty acid oxidation to fulfill the needs of a normoxic high-tubular-workload environment. During stress or injury, the kidney reverts to a fetal signaling program, which is adaptive in the short term, but is deleterious if sustained for prolonged periods when both oxygen tension and tubular workload are heightened. Prolonged increases in glucose uptake in glomerular and proximal tubular cells lead to enhanced flux through the hexosamine biosynthesis pathway; its end product-uridine diphosphate N -acetylglucosamine-drives the rapid and reversible O-GlcNAcylation of thousands of intracellular proteins, typically those that are not membrane-bound or secreted. Both O-GlcNAcylation and phosphorylation act at serine/threonine residues, but whereas phosphorylation is regulated by hundreds of specific kinases and phosphatases, O-GlcNAcylation is regulated only by O-GlcNAc transferase and O-GlcNAcase, which adds or removes N-acetylglucosamine, respectively, from target proteins. Diabetic and nondiabetic CKD is characterized by fetal reprogramming (with upregulation of mTOR and HIF-1 α ) and increased O-GlcNAcylation, both experimentally and clinically. Augmentation of O-GlcNAcylation in the adult kidney enhances oxidative stress, cell cycle entry, apoptosis, and activation of proinflammatory and profibrotic pathways, and it inhibits megalin-mediated albumin endocytosis in glomerular mesangial and proximal tubular cells-effects that can be aggravated and attenuated by augmentation and muting of O-GlcNAcylation, respectively. In addition, drugs with known nephroprotective effects-angiotensin receptor blockers, mineralocorticoid receptor antagonists, and sodium-glucose cotransporter 2 inhibitors-are accompanied by diminished O-GlcNAcylation in the kidney, although the role of such suppression in mediating their benefits has not been explored. The available evidence supports further work on the role of uridine diphosphate N -acetylglucosamine as a critical nutrient surplus sensor (acting in concert with upregulated mTOR and HIF-1 α signaling) in the development of diabetic and nondiabetic CKD.

Effects of Hyaluronan on Breast Cancer Aggressiveness

The expression of the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) in breast cancer cells is critical for determining tumor aggressiveness and targeting therapies. The presence of such receptors allows for the use of antagonists that effectively reduce breast cancer growth and dissemination. However, the absence of such receptors in triple-negative breast cancer (TNBC) reduces the possibility of targeted therapy, making these tumors very aggressive with a poor outcome. Cancers are not solely composed of tumor cells, but also include several types of infiltrating cells, such as fibroblasts, macrophages, and other immune cells that have critical functions in regulating cancer cell behaviors. In addition to these cells, the extracellular matrix (ECM) has become an important player in many aspects of breast cancer biology, including cell growth, motility, metabolism, and chemoresistance. Hyaluronan (HA) is a key ECM component that promotes cell proliferation and migration in several malignancies. Notably, HA accumulation in the tumor stroma is a negative prognostic factor in breast cancer. HA metabolism depends on the fine balance between HA synthesis by HA synthases and degradation yielded by hyaluronidases. All the different cell types present in the tumor can release HA in the ECM, and in this review, we will describe the role of HA and HA metabolism in different breast cancer subtypes.

Immune-independent acquired resistance to PD-L1 antibody initiated by PD-L1 upregulation via PI3K/AKT signaling can be reversed by anlotinib

Despite the benefit with cancer immunotherapies in clinical implication, immunotherapeutic resistance occurred in many patients and the mechanism remains unknown. Increasing evidence has revealed that cell-intrinsic programmed cell death ligand 1 (PD-L1) may play a non-negotiable part in immunotherapeutic resistance. Our present study aimed to elucidate the immune-independent acquired resistance mechanism to PD-L1 antibody. We found elevated PD-L1 expression induced by PD-L1 antibodies in cancer cell and vascular endothelial cells (VECs) with substantially acquired resistance to PD-L1 antibodies. Moreover, proliferation of resistant cells was accelerated and the apoptosis was reduced in the absence of immune compared with parental cells. Subsequently, we confirmed that the activation of the PI3K/AKT pathway is involved in the upregulation of PD-L1 expression. Finally, we found that low dose of anlotinib downregulated PD-L1 expression only in VECs via inhibiting the PI3K/AKT pathway; however, the same effect was not observed in cancer cells. To sum up, our findings revealed that upregulation of PD-L1 via activation of the PI3K/AKT signal pathway may promote acquired resistance to PD-L1 antibodies in an immune-independent manner. SIGNIFICANCE: These findings provide new mechanisms of immunotherapeutic resistance and effective evidence of anlotinib combined with immunotherapy.

Convergent Approaches to Delineate the Metabolic Regulation of Tumor Invasion by Hyaluronic Acid Biosynthesis

Metastasis is the leading cause of breast cancer-related deaths and is often driven by invasion and cancer-stem like cells (CSCs). Both the CSC phenotype and invasion are associated with increased hyaluronic acid (HA) production. How these independent observations are connected, and which role metabolism plays in this process, remains unclear due to the lack of convergent approaches integrating engineered model systems, computational tools, and cancer biology. Using microfluidic invasion models, metabolomics, computational flux balance analysis, and bioinformatic analysis of patient data, the functional links between the stem-like, invasive, and metabolic phenotype of breast cancer cells as a function of HA biosynthesis are investigated. These results suggest that CSCs are more invasive than non-CSCs and that broad metabolic changes caused by overproduction of HA play a role in this process. Accordingly, overexpression of hyaluronic acid synthases (HAS) 2 or 3 induces a metabolic phenotype that promotes cancer cell stemness and invasion in vitro and upregulates a transcriptomic signature predictive of increased invasion and worse patient survival. This study suggests that HA overproduction leads to metabolic adaptations to satisfy the energy demands for 3D invasion of breast CSCs highlighting the importance of engineered model systems and multidisciplinary approaches in cancer research.

The Hexosamine Biosynthesis Pathway: Regulation and Function

The hexosamine biosynthesis pathway (HBP) produces uridine diphosphate-N-acetyl glucosamine, UDP-GlcNAc, which is a key metabolite that is used for N- or O-linked glycosylation, a co- or post-translational modification, respectively, that modulates protein activity and expression. The production of hexosamines can occur via de novo or salvage mechanisms that are catalyzed by metabolic enzymes. Nutrients including glutamine, glucose, acetyl-CoA, and UTP are utilized by the HBP. Together with availability of these nutrients, signaling molecules that respond to environmental signals, such as mTOR, AMPK, and stress-regulated transcription factors, modulate the HBP. This review discusses the regulation of GFAT, the key enzyme of the de novo HBP, as well as other metabolic enzymes that catalyze the reactions to produce UDP-GlcNAc. We also examine the contribution of the salvage mechanisms in the HBP and how dietary supplementation of the salvage metabolites glucosamine and N-acetylglucosamine could reprogram metabolism and have therapeutic potential. We elaborate on how UDP-GlcNAc is utilized for N-glycosylation of membrane and secretory proteins and how the HBP is reprogrammed during nutrient fluctuations to maintain proteostasis. We also consider how O-GlcNAcylation is coupled to nutrient availability and how this modification modulates cell signaling. We summarize how deregulation of protein N-glycosylation and O-GlcNAcylation can lead to diseases including cancer, diabetes, immunodeficiencies, and congenital disorders of glycosylation. We review the current pharmacological strategies to inhibit GFAT and other enzymes involved in the HBP or glycosylation and how engineered prodrugs could have better therapeutic efficacy for the treatment of diseases related to HBP deregulation.

Dysregulation of hexosamine biosynthetic pathway wiring metabolic signaling circuits in cancer

Metabolite sensing, a fundamental biological process, plays a key role in metabolic signaling circuit rewiring. Hexosamine biosynthetic pathway (HBP) is a glucose metabolic pathway essential for the synthesis of uridine diphosphate N-acetylglucosamine (UDP-GlcNAc), which senses key nutrients and integrally maintains cellular homeostasis. UDP-GlcNAc dynamically regulates protein N-glycosylation and O-linked-N-acetylglucosamine modification (O-GlcNAcylation). Dysregulated HBP flux leads to abnormal protein glycosylation, and contributes to cancer development and progression by affecting protein function and cellular signaling. Furthermore, O-GlcNAcylation regulates cellular signaling pathways, and its alteration is linked to various cancer characteristics. Additionally, recent findings have suggested a close association between HBP stimulation and cancer stemness; an elevated HBP flux promotes cancer cell conversion to cancer stem cells and enhances chemotherapy resistance via downstream signal activation. In this review, we highlight the prominent roles of HBP in metabolic signaling and summarize the recent advances in HBP and its downstream signaling, relevant to cancer.

Improved antitumor activity against prostate cancer via synergistic targeting of Myc and GFAT-1

Inhibition of Myc promotes the regression of many types of tumors, including prostate cancer. However, the success of anti-Myc therapy is hampered by the lack of a strategy to effectively deliver the inhibitors to the tumor site and by the feedback mechanisms that cancer cells use to adapt to metabolic reprogramming. Methods: The effects of Myc inhibitors (10074-G5 or 10058-F4), alone or in combination with 6-diazo-5-oxo-L-norleucine (DON), were evaluated in cultured human or murine prostate cancer cells by cell viability assay, qRT-PCR and Western blot. To facilitate the in vivo therapeutic evaluation, a prodrug conjugate of 10074-G4 and DON (10074-DON) was developed, which could be effectively loaded into a polysaccharide-based nanocarrier (PS). Results: The treatment with Myc inhibitors led to significant induction of glutamine: fructose-6-phosphate amidotransferase-1 (GFAT1) and enhanced protein glycosylation. Mechanistically, Myc inhibition triggered GFAT1 induction through the IREα-Xbp1s pathway. The combination use of Myc inhibitors and GFAT1 inhibitor DON led to a synergistic effect in inhibiting the proliferation and migration of prostate cancer cells. Enhanced in vivo delivery of 10074-DON via the PS nanocarrier led to a significant inhibition of tumor growth along with an improvement in tumor immune microenvironment in several PCa animal models. Conclusion: Simultaneous targeting of Myc and GFAT-1 may represent a novel strategy for the treatment of prostate cancer.

SP and KLF Transcription Factors in Cancer Metabolism

Tumor development and progression depend on reprogramming of signaling pathways that regulate cell metabolism. Alterations to various metabolic pathways such as glycolysis, oxidative phosphorylation, lipid metabolism, and hexosamine biosynthesis pathway are crucial to sustain increased redox, bioenergetic, and biosynthesis demands of a tumor cell. Transcription factors (oncogenes and tumor suppressors) play crucial roles in modulating these alterations, and their functions are tethered to major metabolic pathways under homeostatic conditions and disease initiation and advancement. Specificity proteins (SPs) and Krüppel-like factors (KLFs) are closely related transcription factors characterized by three highly conserved zinc fingers domains that interact with DNA. Studies have demonstrated that SP and KLF transcription factors are expressed in various tissues and regulate diverse processes such as proliferation, differentiation, apoptosis, inflammation, and tumorigenesis. This review highlights the role of SP and KLF transcription factors in the metabolism of various cancers and their impact on tumorigenesis. A better understanding of the role and underlying mechanisms governing the metabolic changes during tumorigenesis could provide new therapeutic opportunities for cancer treatment.

A Multistep Tumor Growth Model of High-Grade Serous Ovarian Carcinoma Identifies Hypoxia-Associated Signatures

High-grade serous ovarian carcinoma (HGSC) is associated with late-stage disease presentation and poor prognosis, with a limited understanding of early transformation events. Our study analyzes HGSC tumor progression and organ-specific metastatic dissemination to identify hypoxia-associated molecular, cellular, and histological alterations. Clinical characteristics of the HGSC were replicated in orthotopic xenografts, which involve metastatic dissemination and the prevalence of group B tumors (volume: >0.0625 ≤ 0.5 cm3). Enhanced hyaluronic acid (HA) deposition, expanded tumor vasculature, and increased necrosis contributed to the remodeling of tumor tissue architecture. The proliferative potential of tumor cells and the ability to form glands were also altered during tumor growth. Flow cytometry and label chase-based molecular profiling across the tumor regenerative hierarchy identified the hypoxia-vasculogenic niche and the hybrid epithelial-mesenchymal tumor-cell state as determinants of self-renewal capabilities of progenitors and cancer stem cells. A regulatory network and mathematical model based on tumor histology and molecular signatures predicted hypoxia-inducible factor 1-alpha (HIF1A) as a central node connecting HA synthesis, epithelial-mesenchymal transition, metabolic, vasculogenic, inflammatory, and necrotic pathways in HGSC tumors. Thus, our findings provide a temporal resolution of hypoxia-associated events that sculpt HGSC tumor growth; an in-depth understanding of it may aid in the early detection and treatment of HGSC.

Metabolic targeting of malignant tumors: a need for systemic approach

PURPOSE

Dysregulated metabolism is now recognized as a fundamental hallmark of carcinogenesis inducing aggressive features and additional hallmarks. In this review, well-established metabolic changes displayed by tumors are highlighted in a comprehensive manner and corresponding therapeutical targets are discussed to set up a framework for integrating basic research findings with clinical translation in oncology setting.

METHODS

Recent manuscripts of high research impact and relevant to the field from PubMed (2000-2021) have been reviewed for this article.

RESULTS

Metabolic pathway disruption during tumor evolution is a dynamic process potentiating cell survival, dormancy, proliferation and invasion even under dismal conditions. Apart from cancer cells, though, tumor microenvironment has an acting role as extracellular metabolites, pH alterations and stromal cells reciprocally interact with malignant cells, ultimately dictating tumor-promoting responses, disabling anti-tumor immunity and promoting resistance to treatments.

CONCLUSION

In the field of cancer metabolism, there are several emerging prognostic and therapeutic targets either in the form of gene expression, enzyme activity or metabolites which could be exploited for clinical purposes; both standard-of-care and novel treatments may be evaluated in the context of metabolism rewiring and indeed, synergistic effects between metabolism-targeting and other therapies would be an attractive perspective for further research.

PEGPH20, a PEGylated human hyaluronidase, induces radiosensitization by reoxygenation in pancreatic cancer xenografts. A molecular imaging study

PURPOSE

PEGylated human hyaluronidase (PEGPH20) enzymatically depletes hyaluronan, an important component of the extracellular matrix, increasing the delivery of therapeutic molecules. Combinations of chemotherapy and PEGPH20, however, have been unsuccessful in Phase III clinical trials. We hypothesize that by increasing tumor oxygenation by improving vascular patency and perfusion, PEGPH20 will also act as a radiosensitization agent.

EXPERIMENTAL DESIGN

The effect of PEGPH20 on radiation treatment was analyzed with respect to tumor growth, survival time, p02, local blood volume, and the perfusion/permeability of blood vessels in a human pancreatic adenocarcinoma BxPC3 mouse model overexpressing hyaluronan synthase 3 (HAS3).

RESULTS

Mice overexpressing HAS3 developed fast growing, radiation resistant tumors that became rapidly more hypoxic as time progressed. Treatment with PEGPH20 increased survival times when used in combination with radiation therapy, significantly more than either radiation therapy or PEGPH20 alone. In mice that overexpressed HAS3, EPR imaging showed an increase in local pO2 that could be linked to increases in perfusion/permeability and local blood volume immediately after PEGPH20 treatment. Hyperpolarized [1-13C] pyruvate suggested PEGPH20 caused a metabolic shift towards decreased glycolytic flux. These effects were confined to the mice overexpressing HAS3 - no effect of PEGPH20 on survival, radiation treatment, or pO2 was seen in wild type BxPC3 tumors.

CONCLUSIONS

PEGPH20 may be useful for radiosensitization of pancreatic cancer but only in the subset of tumors with substantial hyaluronan accumulation. The response of the treatment may potentially be monitored by non-invasive imaging of the hemodynamic and metabolic changes in the tumor microenvironment.

Extrinsic hyaluronic acid induction differentially modulates intracellular glutamine metabolism in breast cancer stem cells

The effect of low and high molecular weight hyaluronic acid on glutamine metabolism in luminal and basal breast cancer and cancer stem cells is being investigated. In luminal cell lines (MCF-7), HA enhances the intracellular utilization of gln in redox metabolism and decreases its use in TCA. On the contrary, in MDAMB-231 cells, HA induces the uptake of gln to be utilized in anaplerosis rather than ROS maintenance. However, in MCF-7 CSCs, HA induces up-regulation of xCT, further, it uses gln-derived glutamate for the exchange of cystine, thus maintaining ROS levels through xCT. MDA-MB-231 CSCs reduce the secretion of glutamate in response to HA and decrease the gln flux towards reductive carboxylation. Conclusively, our study demonstrated that although the uptake of gln is enhanced by HA, it is differentially utilized intracellularly in breast cancer cells. This study could significantly influence the therapeutics involving HA and Gln in breast cancer.

Hyaluronan network: a driving force in cancer progression

Hyaluronan is one of the most abundant macromolecules of the extracellular matrix and regulates several physiological cell and tissue properties. However, hyaluronan has been shown to accumulate together with its receptors in various cancers. In tumors, accumulation of hyaluronan system components (hyaluronan synthesizing/degrading enzymes and interacting proteins) associates with poor outcomes of the patients. In this article, we review the main roles of hyaluronan in normal physiology and cancer, and further discuss the targeting of hyaluronan system as an applicable therapeutic strategy.

LncRNA LINC00649 promotes the growth and metastasis of triple-negative breast cancer by maintaining the stability of HIF-1α through the NF90/NF45 complex

There is no clear treatment guideline or individualized treatment plan for triple-negative breast cancer (TNBC). The aim of this study was to investigate more effective targets for TNBC-targeted therapy. MDA-MB-231 and BT549 cell lines were used to explore the function of LINC00649 on the proliferation, invasion, and migration of TNBC cells. A mice subcutaneous tumor model and a pulmonary metastasis model was established to identify the role of LINC00649 on the growth and metastasis of TNBC in vivo. LINC00649 was found to be a key molecule involved in the occurrence and development of TNBC by screening of public databases and detection of TNBC clinical samples. LINC00649 increased hypoxia-inducible factor 1α (HIF-1α) mRNA stability and protein expression by interacting with the nuclear factor 90 (NF90)/NF45 complex. In vitro, interference with LINC00649 inhibits MDA-MB-231 and BT549 cell proliferation, migration, and invasion, and the addition of HIF-1α revised this effect. In vivo experiments showed that LINC00649 promoted the growth and metastasis of TNBC. We demonstrated that LINC00649 interacts with the NF90/NF45 complex to increase the mRNA stability of HIF-1α and up-regulate HIF-1α expression, thereby inducing the proliferation, invasion, and migration of TNBC cells as well as tumor growth and metastasis.

Endogenously-Produced Hyaluronan and Its Potential to Regulate the Development of Peritoneal Adhesions

Formation of peritoneal adhesions (PA) is one of the major complications following intra-abdominal surgery. It is primarily caused by activation of the mesothelial layer and underlying tissues in the peritoneal membrane resulting in the transition of mesothelial cells (MCs) and fibroblasts to a pro-fibrotic phenotype. Pro-fibrotic transition of MCs—mesothelial-to-mesenchymal transition (MMT), and fibroblasts activation to myofibroblasts are interconnected to changes in cellular metabolism and culminate in the deposition of extracellular matrix (ECM) in the form of fibrotic tissue between injured sides in the abdominal cavity. However, ECM is not only a mechanical scaffold of the newly synthetized tissue but reciprocally affects fibrosis development. Hyaluronan (HA), an important component of ECM, is a non-sulfated glycosaminoglycan consisting of N-acetyl-D-glucosamine (GlcNAc) and D-glucuronic acid (GlcUA) that can affect the majority of processes involved in PA formation. This review considers the role of endogenously produced HA in the context of different fibrosis-related pathologies and its overlap in the development of PA.

Cancer Stem Cell for Tumor Therapy

Simple Summary

Although many methods have been applied in clinical treatment for tumors, they still always show a poor prognosis. Molecule targeted therapy has revolutionized tumor therapy, and a proper target must be found urgently. With a crucial role in tumor development, metastasis and recurrence, cancer stem cells have been found to be a feasible and potential target for tumor therapy. We list the unique biological characteristics of cancer stem cells and summarize the recent strategies to target cancer stem cells for tumor therapy, through which we hope to provide a comprehensive understanding of cancer stem cells and find a better combinational strategy to target cancer stem cells for tumor therapy.

Abstract

Tumors pose a significant threat to human health. Although many methods, such as operations, chemotherapy and radiotherapy, have been proposed to eliminate tumor cells, the results are unsatisfactory. Targeting therapy has shown potential due to its specificity and efficiency. Meanwhile, it has been revealed that cancer stem cells (CSCs) play a crucial role in the genesis, development, metastasis and recurrence of tumors. Thus, it is feasible to inhibit tumors and improve prognosis via targeting CSCs. In this review, we provide a comprehensive understanding of the biological characteristics of CSCs, including mitotic pattern, metabolic phenotype, therapeutic resistance and related mechanisms. Finally, we summarize CSCs targeted strategies, including targeting CSCs surface markers, targeting CSCs related signal pathways, targeting CSC niches, targeting CSC metabolic pathways, inducing differentiation therapy and immunotherapy (tumor vaccine, CAR-T, oncolytic virus, targeting CSCs–immune cell crosstalk and immunity checkpoint inhibitor). We highlight the potential of immunity therapy and its combinational anti-CSC therapies, which are composed of different drugs working in different mechanisms.

Biglycan reduces body weight by regulating food intake in mice and improves glucose metabolism through AMPK/AKT dual pathways in skeletal muscle

While biglycan (BGN) is suggested to direct diverse signaling cascades, the effects of soluble BGN as a ligand on metabolic traits have not been studied. Herein, we tested the effects of BGN on obesity in high-fat diet (HFD)-induced obese animals and glucose metabolism, with the underlying mechanism responsible for observed effects in vitro. Our results showed that BGN administration (1 mg/kg body weight, intraperitoneally) significantly prevented HFD-induced obesity, and this was mainly attributed to reduced food intake. Also, intracerebroventricular injection of BGN reduced food intake and body weight. The underlying mechanism includes modulation of neuropeptides gene expression involved in appetite in the hypothalamus in vitro and in vivo. In addition, BGN regulates glucose metabolism as shown by improved glucose tolerance in mice as well as AMPK/AKT dual pathway-driven enhanced glucose uptake and GLUT4 translocation in L6 myoblast cells. In conclusion, our results suggest BGN as a potential therapeutic target to treat risk factors for metabolic diseases.

Stromal hyaluronan accumulation is associated with low immune response and poor prognosis in pancreatic cancer

Hyaluronan (HA) accumulation has been associated with poor survival in various cancers, but the mechanisms for this phenomenon are still unclear. The aim of this study was to investigate the prognostic significance of stromal HA accumulation and its association with host immune response in pancreatic ductal adenocarcinoma (PDAC). The study material consisted of 101 radically treated patients for PDAC from a single geographical area. HA staining was evaluated using a HA-specific probe, and the patterns of CD3, CD8, CD73 and PD-L1 expression were evaluated using immunohistochemistry. HA staining intensity of tumour stromal areas was assessed digitally using QuPath. CD3- and CD8-based immune cell score (ICS) was determined. High-level stromal HA expression was significantly associated with poor disease-specific survival (p = 0.037) and overall survival (p = 0.013) In multivariate analysis, high-level stromal HA expression was an independent negative prognostic factor together with histopathological grade, TNM stage, CD73 positivity in tumour cells and low ICS. Moreover, high-level stromal HA expression was associated with low ICS (p = 0.017). In conclusion, stromal HA accumulation is associated with poor survival and low immune response in PDAC.

The hexosamine biosynthetic pathway and cancer: Current knowledge and future therapeutic strategies

The hexosamine biosynthetic pathway (HBP) is a glucose metabolism pathway that results in the synthesis of a nucleotide sugar UDP-GlcNAc, which is subsequently used for the post-translational modification (O-GlcNAcylation) of intracellular proteins that regulate nutrient sensing and stress response. The HBP is carried out by a series of enzymes, many of which have been extensively implicated in cancer pathophysiology. Increasing evidence suggests that elevated activation of the HBP may act as a cancer biomarker. Inhibition of HBP enzymes could suppress tumor cell growth, modulate the immune response, reduce resistance, and sensitize tumor cells to conventional cancer therapy. Therefore, targeting the HBP may serve as a novel strategy for treating cancer patients. Here, we review the current findings on the significance of HBP enzymes in various cancers and discuss future approaches for exploiting HBP inhibition for cancer treatment.

The Secreted Protein C10orf118 Is a New Regulator of Hyaluronan Synthesis Involved in Tumour-Stroma Cross-Talk

Simple Summary

Hyaluronan is a main glycosaminoglycan in extracellular matrix with an important role in breast cancer progression. Alterations in its synthesis and size may affect tu-mour growth and metastasis. Communication between stromal and breast cancer cells consists of the secretion of factors that provoke a series of cell signalling that influence cell fate and tis-sue microenvironment, by favouring tumour cell survival and motility. Here, we present the c10orf118 protein expressed in high amounts by breast tumour cells as a new regulator in hya-luronan synthesis. This protein is found both in Golgi and secreted in the extracellular matrix, whereas its role is still unknown. The secreted c10orf118 is found to induce hyaluronan synthase 2 in normal fibroblasts. Importantly, high expression of c10orf118 is positively correlated to pa-tient’s survival and to a low metastasis.

Abstract

Interaction between cancer cells and their microenvironment is central in defining the fate of cancer development. Tumour cells secrete signals (cytokines, chemokines, growth factors) that modify the surrounding area, while the niche supplies structures and activities necessary for tumour maintenance and growth. Hyaluronan (HA) is a glycosaminoglycan that constitute cancer cell niche and is known to influence tumour functions such as proliferation, migration and neoangiogenesis. The knowledge of the factors regulating HA synthesis and size is crucial in understanding the mechanisms sustaining tumour development. Here we show that a yet uncharacterized protein secreted by breast tumour cell lines, named c10orf118 (accession number NM_018017 in NCBI/BLAST, and Q7z3E2 according to the Uniprot identifier), with a predicted length of 898 amino acids, can induce the secretion of HA by stromal fibroblasts through the up-regulation of the hyaluronan synthase 2 gene (HAS2). Intracellularly, this protein is localized in the Golgi apparatus with a possible role in vesicle maturation and transport. The expression of c10orf118 was verified in breast cancer patient specimens and was found to be associated with the presence of estrogen receptor that characterizes a good patient survival. We suggest c10orf118 as a new player that influences the HA amount in breast cancer microenvironment and is associated with low aggressiveness of cancer.

Cell Energy Metabolism and Hyaluronan Synthesis

Hyaluronan (HA) is a linear glycosaminoglycan (GAG) of extracellular matrix (ECM) synthesized by three hyaluronan synthases (HASes) at the plasma membrane using uridine diphosphate (UDP)-glucuronic acid (UDP-GlcUA) and UDP-N-acetylglucosamine (UDP-GlcNAc) as substrates. The production of HA is mainly regulated by hyaluronan synthase 2 (HAS2), that can be controlled at different levels, from epigenetics to transcriptional and post-translational modifications. HA biosynthesis is an energy-consuming process and, along with HA catabolism, is strongly connected to the maintenance of metabolic homeostasis. The cytoplasmic pool of UDP-sugars is critical for HA synthesis. UDP-GlcNAc is an important nutrient sensor and serves as donor substrate for the O-GlcNAcylation of many cytosolic proteins, including HAS2. This post-translational modification stabilizes HAS2 in the membrane and increases HA production. Conversely, HAS2 can be phosphorylated by AMP activated protein kinase (AMPK), a master metabolic regulator activated by low ATP/AMP ratios, which inhibits HA secretion. Similarly, HAS2 expression and the deposition of HA within the pericellular coat are inhibited by sirtuin 1 (SIRT1), another important energetic sensor, confirming the tight connection between nutrients availability and HA metabolism.

The Tumor Microenvironment as a Driving Force of Breast Cancer Stem Cell Plasticity

Simple Summary

Breast cancer stem cells are a subset of transformed cells that sustain tumor growth and can metastasize to secondary organs. Since metastasis accounts for most cancer deaths, it is of paramount importance to understand the cellular and molecular mechanisms that regulate this subgroup of cells. The tumor microenvironment (TME) is the habitat in which transformed cells evolve, and it is composed by many different cell types and the extracellular matrix (ECM). A body of evidence strongly indicates that microenvironmental cues modulate stemness in breast cancer, and that the coevolution of the TME and cancer stem cells determine the fate of breast tumors. In this review, we summarize the studies providing links between the TME and the breast cancer stem cell phenotype and we discuss their specific interactions with immune cell subsets, stromal cells, and the ECM.

Abstract

Tumor progression involves the co-evolution of transformed cells and the milieu in which they live and expand. Breast cancer stem cells (BCSCs) are a specialized subset of cells that sustain tumor growth and drive metastatic colonization. However, the cellular hierarchy in breast tumors is rather plastic, and the capacity to transition from one cell state to another depends not only on the intrinsic properties of transformed cells, but also on the interplay with their niches. It has become evident that the tumor microenvironment (TME) is a major player in regulating the BCSC phenotype and metastasis. The complexity of the TME is reflected in its number of players and in the interactions that they establish with each other. Multiple types of immune cells, stromal cells, and the extracellular matrix (ECM) form an intricate communication network with cancer cells, exert a highly selective pressure on the tumor, and provide supportive niches for BCSC expansion. A better understanding of the mechanisms regulating these interactions is crucial to develop strategies aimed at interfering with key BCSC niche factors, which may help reducing tumor heterogeneity and impair metastasis.

Hyaluronan: Metabolism and Function

As a major polysaccharide component of the extracellular matrix, hyaluronan plays essential roles in the organization of tissue architecture and the regulation of cellular functions, such as cell proliferation and migration, through interactions with cell-surface receptors and binding molecules. Metabolic pathways for biosynthesis and degradation tightly control the turnover rate, concentration, and molecular size of hyaluronan in tissues. Despite the relatively simple chemical composition of this polysaccharide, its wide range of molecular weights mediate diverse functions that depend on molecular size and tissue concentration. Genetic engineering and pharmacological approaches have demonstrated close associations between hyaluronan metabolism and functions in many physiological and pathological events, including morphogenesis, wound healing, and inflammation. Moreover, emerging evidence has suggested that the accumulation of hyaluronan extracellular matrix and fragments due to the altered expression of hyaluronan synthases and hyaluronidases potentiates cancer development and progression by remodeling the tumor microenvironment. In addition to the well-known functions exerted by extracellular hyaluronan, recent metabolomic approaches have also revealed that its synthesis can regulate cellular functions via the reprogramming of cellular metabolism. This review highlights the current advances in knowledge on the biosynthesis and catabolism of hyaluronan and describes the diverse functions associated with hyaluronan metabolism.

Cancer-Associated Fibroblasts: Accomplices in the Tumor Immune Evasion

Simple Summary

A growing number of studies suggest that cancer-associated fibroblasts (CAFs) modulate both myeloid and lymphoid cells through secretion of molecules (i.e., chemical function) and production of the extracellular matrix (ECM), i.e., physical function. Even though targeting functions CAFs is a relevant strategy, published clinical trials solely aimed at targeting the stroma showed disappointing results, despite being based on solid preclinical evidence. Our review dissects the interactions between CAFs and immune cells and explains how a deeper understanding of CAF subpopulations is the cornerstone to propose relevant therapies that will ultimately improve survival of patients with cancer.

Abstract

Cancer-associated fibroblasts (CAFs) are prominent cells within the tumor microenvironment, by communicating with other cells within the tumor and by secreting the extracellular matrix components. The discovery of the immunogenic role of CAFs has made their study particularly attractive due to the potential applications in the field of cancer immunotherapy. Indeed, CAFs are highly involved in tumor immune evasion by physically impeding the immune system and interacting with both myeloid and lymphoid cells. However, CAFs do not represent a single cell entity but are divided into several subtypes with different functions that may be antagonistic. Considering that CAFs are orchestrators of the tumor microenvironment and modulate immune cells, targeting their functions may be a promising strategy. In this review, we provide an overview of (i) the mechanisms involved in immune regulation by CAFs and (ii) the therapeutic applications of CAFs modulation to improve the antitumor immune response and the efficacy of immunotherapy.

The tumour microenvironment in pancreatic cancer - clinical challenges and opportunities

Metastatic pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal solid tumours despite the use of multi-agent conventional chemotherapy regimens. Such poor outcomes have fuelled ongoing efforts to exploit the tumour microenvironment (TME) for therapy, but strategies aimed at deconstructing the surrounding desmoplastic stroma and targeting the immunosuppressive pathways have largely failed. In fact, evidence has now shown that the stroma is multi-faceted, which illustrates the complexity of exploring features of the TME as isolated targets. In this Review, we describe ways in which the PDAC microenvironment has been targeted and note the current understanding of the clinical outcomes that have unexpectedly contradicted preclinical observations. We also consider the more sophisticated therapeutic strategies under active investigation - multi-modal treatment approaches and exploitation of biologically integrated targets - which aim to remodel the TME against PDAC.

Modulating microenvironments for treating glioblastoma

Purpose of review

This review focuses on the development and progression of glioblastoma through the brain and glioma microenvironment. Specifically we highlight how the tumor microenvironment contributes to the hallmarks of cancer in hopes of offering novel therapeutic options and tools to target this microenvironment.

Recent findings

The hallmarks of cancer, which represent elements of cancers that contribute to the disease's malignancy, yet elements within the brain tumor microenvironment, such as other cellular types as well as biochemical and biophysical cues that can each uniquely affect tumor cells, have not been well-described in this context and serve as potential targets for modulation.

Summary

Here, we highlight how the brain tumor microenvironment contributes to the progression and therapeutic response of tumor cells. Specifically, we examine these contributions through the lens of Hanahan & Weinberg's Hallmarks of Cancer in order to identify potential novel targets within the brain that may offer a means to treat brain cancers, including the deadliest brain cancer, glioblastoma.

Targeting tumor-intrinsic hexosamine biosynthesis sensitizes pancreatic cancer to anti-PD1 therapy

Pancreatic ductal adenocarcinoma (PDAC) is considered to be a highly immunosuppressive and heterogenous neoplasm. Despite improved knowledge regarding the genetic background of the tumor and better understanding of the tumor microenvironment, immune checkpoint inhibitor therapy (targeting CTLA4, PD1, PDL1) has not been very successful against PDAC. The robust desmoplastic stroma, along with an extensive extracellular matrix (ECM) that is rich in hyaluronan, plays an integral role in this immune evasion. Hexosamine biosynthesis pathway (HBP), a shunt pathway of glycolysis, is a metabolic node in cancer cells that can promote survival pathways on the one hand and influence the hyaluronan synthesis in the ECM on the other. The rate-limiting enzyme of the pathway, glutamine-fructose amidotransferase 1 (GFAT1), uses glutamine and fructose 6-phosphate to eventually synthesize uridine diphosphate N-acetylglucosamine (UDP-GlcNAc). In the current manuscript, we targeted this glutamine-utilizing enzyme by a small molecule glutamine analog (6-diazo-5-oxo-l-norleucine [DON]). Our results showed that DON decreased the self-renewal potential and metastatic ability of tumor cells. Further, treatment with DON decreased hyaluronan and collagen in the tumor microenvironment, leading to an extensive remodeling of the ECM and an increased infiltration of CD8+ T cells. Additionally, treatment with DON sensitized pancreatic tumors to anti-PD1 therapy, resulting in tumor regression and prolonged survival.

Vitamin D regulation of HAS2, hyaluronan synthesis and metabolism in triple negative breast cancer cells

The vitamin D receptor (VDR) and its ligand 1,25(OH)₂D₃ (1,25D) exert anti-tumor effects, but considerable heterogeneity has been reported in different model systems. In general, cell lines derived from aggressive tumor subtypes such as Triple Negative Breast Cancer (TNBC) express low levels of VDR and are less sensitive to 1,25D than those derived from more differentiated tumor types. We have previously reported that 1,25D inhibits hyaluronic acid synthase 2 (HAS2) expression and hyaluronic acid (HA) synthesis in murine TNBC cells. Here we confirmed the inhibitory effect of 1,25D on HA synthesis in human Hs578T cells representative of the mesenchymal/stem-like (MSL) subtype of TNBC. Because HA synthesis requires the production of hexoses for incorporation into HA, we predicted that the high HA production characteristic of Hs578T cells would require sustained metabolic changes through the hexosamine biosynthetic pathway (HBP). We thus examined metabolic gene expression in Hs578T cell variants sorted for High (HA^High) and Low (HA^Low) HA production, and the ability of 1,25D to reverse these adaptive changes. HA^High populations exhibited elevated HA production, smaller size, increased proliferation and higher motility than HA^Low populations. Despite their more aggressive phenotype, HA^High populations retained expression of VDR protein at levels comparable to that of parental Hs578T cells and HA^Low subclones. Treatment with 1,25D decreased production of HA in both HA^High and HA^Low populations. We also found that multiple metabolic enzymes were aberrantly expressed in HA^High cells, especially those involved in glutamine and glucose metabolism. Notably, Glutaminase (GLS), a known oncogene for breast cancer, was strongly upregulated in HA^High vs. HA^Low cells and its expression was significantly reduced by 1,25D (100 nM, 24 h). Consistent with this finding, Seahorse extracellular flux analysis indicated that respiration in HA^High cells was significantly more dependent on exogenous glutamine than HA^Low cells, however, acute 1,25D exposure did not alter metabolic flux. In contrast to GLS, the glutamate transporter SLC1A7 was significantly reduced in HA^High cells compared to HA^Low cells and its expression was enhanced by 1,25D. These findings support the concept that 1,25D can reverse the metabolic gene expression changes associated with HA production in cancer cells with aggressive phenotypes.

3D culture technologies of cancer stem cells: promising ex vivo tumor models

Cancer stem cells have been shown to be important in tumorigenesis processes, such as tumor growth, metastasis, and recurrence. As such, many three-dimensional models have been developed to establish an ex vivo microenvironment that cancer stem cells experience under in vivo conditions. Cancer stem cells propagating in three-dimensional culture systems show physiologically related signaling pathway profiles, gene expression, cell-matrix and cell-cell interactions, and drug resistance that reflect at least some of the tumor properties seen in vivo. Herein, we discussed the presently available Cancer stem cell three-dimensional culture models that use biomaterials and engineering tools and the biological implications of these models compared to the conventional ones.

Hyaluronic acid binding to CD44S is indiscriminate of molecular weight

The ubiquitous presence of hyaluronic acid (HA) in the extracellular matrix (ECM) of both healthy and diseased tissues underscores its importance in human physiology. Previous studies suggest that HA can be used as a probe to qualitatively monitor cell surface levels of CD44 and other important HA receptors; however, these studies use mixtures of HA at various molecular weights. Using fluorescently labeled HA, we evaluated the apparent differences of low (25 kilodalton) and high (700 kilodalton) molecular weight HA interacting with breast cancer cell lines of varying levels of CD44. Our results confirm that CD44 expression and the apparent level of HA interaction correlates with molecular weight. Importantly, we show that HA only binds a small fraction of the major CD44 isoform, CD44S, on cell surfaces and that CD44S interactions account for <50% of the total HA bound to cell surfaces. Although increased fluorescence level correlates with higher molecular weight of HA, this appears to be an artifact of chain length and not a result of multivalent binding between HA and CD44S. Accordingly, we verify that HA binding characteristics of cell surfaces is similar to previous artificial membrane models which proposed that HA anchors to CD44S and forms a non-binding corona of HA that extends beyond the surface.

Suppression of murine osteoarthritis by 4-methylumbelliferone

Using in vitro models, we previously reported that 4-methylumbelliferone (4-MU) blocked many of the pro-catabolic features of activated chondrocytes. 4-MU also blocked safranin O loss from human cartilage explants exposed to interleukin 1β (IL1β) in vitro. However, the mechanism for this chondroprotective effect was independent of the action of 4-MU as a hyaluronan (HA) inhibitor. Interestingly, overexpression of HA synthase 2 (HAS2) also blocked the same pro-catabolic features of activated chondrocytes as 4-MU via a mechanism independent of extracellular HA accumulation. Data suggest that altering UDP-sugars may be behind these changes in chondrocyte metabolism. However, all of our previous experiments with 4-MU or HAS2 overexpression were performed in vitro. The purpose of this study was to confirm whether 4-MU was effective at limiting the effects of osteoarthritis (OA) on articular cartilage in vivo. The progression of OA was evaluated after destabilization of the medial meniscus (DMM) surgery on C57BL/6 mice in the presence or absence of 4-MU-containing chow. Mice fed 4-MU after DMM surgery exhibited significant suppression of OA starting from an early stage in vivo. Mice fed 4-MU exhibited lower OARSI scores after DMM; reduced osteophyte formation and reduced MMP3 and MMP13 immunostaining. 4-MU also exerted pronounced chondroprotective effects on murine joint cartilage exposed to IL1β in vitro and, blocked IL1β-enhanced lactate production in cartilage explants. Therefore, 4-MU is effective at significantly reducing the loss of proteoglycan and reducing MMP production both in vitro and in vivo as well as cartilage damage and osteophyte formation in vivo after DMM. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. 38:1122-1131, 2020.

Hyaluronan Induces a Mitochondrial Functional Switch in Fast-Proliferating Human Mesenchymal Stem

Background and Objectives

Hyaluronan preserves the proliferation and differentiation potential of mesenchymal stem cells. Supplementation of low-concentration hyaluronan (SHA) in stem cells culture medium increases its proliferative rate, whereas coated-surface hyaluronan (CHA) maintains cells in a slow-proliferating mode. We have previously demonstrated that in CHA, the metabolic proliferative state of stem cells was influenced by upregulating mitochondrial biogenesis and function. However, the effect of SHA on stem cells' energetic status remains unknown. In this study, we demonstrate the effect that low-concentration SHA at 0.001 mg/ml (SHA0.001) and high-concentration SHA at 5 mg/ml (SHA5) exert on stem cells' mitochondrial function compared with CHA and noncoated tissue culture surface (control).

Methods and Results

Fast-proliferating human placenta-derived mesenchymal stem cells (PDMSCs) cultured on SHA0.001 exhibited reduced mitochondrial mass, lower mitochondrial DNA copy number, and lower oxygen consumption rate compared with slow-proliferating PDMSCs cultured on CHA at 5.0 (CHA5) or 30 μg/cm² (CHA30). The reduced mitochondrial biogenesis observed in SHA0.001 was accompanied by a 2-fold increased ATP content and lactate production, suggesting that hyaluronan-induced fast-proliferating PDMSCs may rely less on mitochondrial function as an energy source and induce a mitochondrial functional switch to glycolysis.

Conclusions

PDMSCs cultured on both CHA and SHA exhibited a reduction in reactive oxygen species levels. The results from this study clarify our understandings on the effect of hyaluronan on stem cells and provide important insights into the effect of distinct supplementation methods used during cell therapies.

GFAT1/HBP/O-GlcNAcylation Axis Regulates β-Catenin Activity to Promote Pancreatic Cancer Aggressiveness

Reprogrammed glucose and glutamine metabolism are essential for tumor initiation and development. As a branch of glucose and metabolism, the hexosamine biosynthesis pathway (HBP) generates uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) and contributes to the O-GlcNAcylation process. However, the spectrum of HBP-dependent tumors and the mechanisms by which the HBP promotes tumor aggressiveness remain areas of active investigation. In this study, we analyzed the activity of the HBP and its prognostic value across 33 types of human cancers. Increased HBP activity was observed in pancreatic ductal adenocarcinoma (PDAC), and higher HBP activity predicted a poor prognosis in PDAC patients. Genetic silencing or pharmacological inhibition of the first and rate-limiting enzyme of the HBP, glutamine:fructose-6-phosphate amidotransferase 1 (GFAT1), inhibited PDAC cell proliferation, invasive capacity, and triggered cell apoptosis. Notably, these effects can be restored by addition of UDP-GlcNAc. Moreover, similar antitumor effects were noticed by pharmacological inhibition of GFAT1 with 6-diazo-5-oxo-l-norleucine (DON) or Azaserine. PDAC is maintained by oncogenic Wnt/β-catenin transcriptional activity. Our data showed that GFAT1 can regulate β-catenin expression via modulation of the O-GlcNAcylation process. TOP/FOP-Flash and real-time qPCR analysis showed that GFAT1 knockdown inhibited β-catenin activity and the transcription of its downstream target genes CCND1 and MYC. Ectopic expression of a stabilized form of β-catenin restored the suppressive roles of GFAT1 knockdown on PDAC cell proliferation and invasion. Collectively, our findings indicate that higher GFAT1/HBP/O-GlcNAcylation exhibits tumor-promoting roles by maintaining β-catenin activity in PDAC.

Long non‑coding RNA profile revealed by microarray indicates that lncCUEDC1 serves a negative regulatory role in breast cancer stem cells

Previous studies have demonstrated that long non‑coding RNAs (lncRNAs) are involved in breast cancer development, progression and metastasis. However, the association between lncRNAs and breast cancer stem cells (BCSCs) has been poorly explored. To address this issue, microarray analyses were performed to detect the lncRNA profile of BCSCs. In addition, bioinformatics analyses, including Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes pathway analyses, were performed to explore the functional roles of lncRNAs in BCSCs. Lastly, loss of function assays were used to explore the potential function of lncRNA CUE domain containing 1 (lncCUEDC1). A total of 142 differentially expressed lncRNAs were identified. Among these, 25 were downregulated and 117 were upregulated in BCSCs compared with in non‑BCSCs. In addition, the present study revealed that the lncRNAs were largely associated with stemness‑related signaling pathways. Furthermore, it was demonstrated that lncCUEDC1 negatively regulated the phenotype and biological functions of BCSCs in vitro. Mechanistically, lncCUEDC1 could bind NANOG to inhibit the stemness. To the best of our knowledge, the present study was the first to established the lncRNA profile of BCSCs. These findings provided evidence for exploring the functions of lncRNAs in BCSCs and indicated that lncCUEDC1 is a prospective target in BCSCs.

Enhanced hexosamine metabolism drives metabolic and signaling networks involving hyaluronan production and O-GlcNAcylation to exacerbate breast cancer

The hexosamine biosynthetic pathway (HBP) metabolically regulates dynamic cellular events by linking nutrient availability to numerous signaling networks. Significant alterations in the HBP are often associated with cancer pathogenesis. In this study, we investigated the molecular events underlying cancer pathogenesis associated with enhanced HBP flux. Multidimensional analysis of microarray datasets demonstrated up-regulation of genes encoding HBP enzymes in clinical breast cancers and revealed that co-expression of hyaluronan synthase 2 (HAS2) and glutamine:fructose-6-phosphate amidotransferase (GFAT), a rate-limiting enzyme of the HBP, was strongly correlated with a poor prognosis in advanced cancer patients. Consistently with the clinical data, comparative analyses of distinct breast cancer mouse models demonstrated enhancement of the HBP gene expression in primary carcinoma cells, with elevation of Has2 expression and hyaluronan production in aggressive breast cancer cells. The silencing of GFAT reduced CD44high/CD24low cancer stem cell (CSC)-like subpopulations, aldehyde dehydrogenase-positive cell populations, and mammosphere size, which were further diminished by gene targeting of Has2. Has2 gene disruption reduced the in vivo growth of aggressive cancer cells and attenuated pro-tumorigenic Akt/GSK3β/β-catenin signaling and cisplatin resistance. Overall protein O-GlcNAcylation was also elevated in association with HBP enhancement in aggressive cancer cells, and the modification exhibited overlapping but distinct roles from the hyaluronan signal in the regulation of CSC-like features. The current data therefore demonstrate that enhanced hexosamine metabolism drives pro-tumorigenic signaling pathways involving hyaluronan and O-GlcNAcylation in aggressive breast cancer.

Chondroprotective effects of 4-methylumbelliferone and hyaluronan synthase-2 overexpression involve changes in chondrocyte energy metabolism

Hyaluronan is a critical component of articular cartilage and partially helps retain aggrecan within the extracellular matrix of this tissue. During osteoarthritis, hyaluronan and aggrecan loss are an early sign of tissue damage. However, our recent attempts to mimic hyaluronan loss with the hyaluronan inhibitor 4-methylumbelliferone (4MU) did not exacerbate arthritis-like features of in vitro models of arthritis, but surprisingly, caused the reverse (i.e. provided potent chondroprotection). Moreover, the protective effects of 4MU did not depend on its role as a hyaluronan inhibitor. To understand the molecular mechanism in 4MU-mediated chondroprotection, we considered recent studies suggesting that shifts in intracellular UDP-hexose pools promote changes in metabolism. To determine whether such metabolic shifts are associated with the mechanism of 4MU-mediated pro-catabolic inhibition, using molecular and metabolomics approaches, we examined whether bovine and human chondrocytes exhibit changes in the contribution of glycolysis and mitochondrial respiration to ATP production rates as well as in other factors that respond to or might drive these changes. Overexpression of either HA synthase-2 or 4MU effectively reduced dependence on glycolysis in chondrocytes, especially enhancing glycolysis use by interleukin-1β (IL1β)-activated chondrocytes. The reduction in glycolysis secondarily enhanced mitochondrial respiration in chondrocytes, which, in turn, rescued phospho-AMP-activated protein kinase (AMPK) levels in the activated chondrocytes. Other glycolysis inhibitors, unrelated to hyaluronan biosynthesis, namely 2-deoxyglucose and dichloroacetate, caused metabolic changes in chondrocytes equivalent to those elicited by 4MU and similarly protected both chondrocytes and cartilage explants. These results suggest that fluxes in UDP-hexoses alter metabolic energy pathways in cartilage.

Hyaluronan-CD44 axis orchestrates cancer stem cell functions

The prominent role of CD44 in tumor cell signaling together with its establishment as a cancer stem cell (CSC) marker for various tumor entities imply a key role for CD44 in CSC functional properties. Hyaluronan, the main ligand of CD44, is a major constituent of CSC niche and, therefore, the hyaluronan-CD44 signaling axis is of functional importance in this special microenvironment. This review aims to provide recent advances in the importance of hyaluronan-CD44 interactions in the acquisition and maintenance of a CSC phenotype. Hyaluronan-CD44 axis has a substantial impact on stemness properties of CSCs and drug resistance through induction of EMT program, oxidative stress resistance, secretion of extracellular vesicles/exosomes and epigenetic control. Potential therapeutic approaches targeting CSCs based on the hyaluronan-CD44 axis are also presented.