Targeting galectin-driven regulatory circuits in cancer and fibrosis

A novel pectin-like polysaccharide from Crocus sativus targets Galectin-3 to inhibit hepatic stellate cells activation and liver fibrosis

Liver fibrosis may lead to cirrhosis and even cancer without effective clinical medicine available. Previous studies demonstrated that galactan-containing pectins or pectin-like polysaccharides might target Galectin-3 (Gal-3) to impede fibrosis. This research aims to discover novel pectin-like galactan to interfere with fibrosis for potential new drug development. Thus, we purify a novel homogeneous Rhamnogalacturonan-I like polysaccharide with galactan input, XHH2, from the Crocus sativus flower. XHH2 (MW: 35.7 kDa) consists of rhamnose, galacturonic acid, galactose, and arabinose in ratios of 6.6: 6.1: 25.2: 12.1. The backbone of XHH2 comprises 1, 3, 6-Gal and 1, 3, 4-GalA, with branches at O-3 of 1, 3, 6-Gal and O-4 of 1, 3, 4-GalA. O-3 branches include 1, 3-Gal, 1, 4-Gal, 1, 6-Gal, T-Gal, and T-Glc, while O-4 branches consist of 1, 2, 4-Rha, 1, 4-GalA, 1, 5-Ara, T-Ara, T-Gal, and T-α-HexA. Surface plasmon resonance measurement shows that XHH2 binds to both Gal-3 and integrin β1 to block Gal-3/integrin β1 interaction. Mechanism studies further suggest that XHH2 inactivates hepatic stellate cells (HSCs) via disturbing the Gal-3/Integrin-β1/FAK pathway to alleviate liver injury and fibrosis in vitro & in vivo. XHH2 shows a favorable drug safety in the acute toxicity test of oral administration of XHH2 in mice. Overall, XHH2 is an active ingredient against liver fibrosis by targeting the interaction between Gal-3 and Integrin-β1.

Modeling the Detailed Conformational Effects of the Lactosylation of Hyaluronic Acid

Hyaluronic acid (HA) is a natural and biocompatible polysaccharide that is able to interact with CD44 receptors to regulate inflammation, fibrosis, and tissue reconstruction. It is a suitable chemical scaffold for drug delivery that can be functionalized with pharmacophores and/or vectorizable groups. The derivatization of HA is achieved to varying extents by reacting 1-amino-1-deoxy-lactitol via the carboxyl group to form amide linkages, giving rise to the grafted polymer, HYLACH. This retains the broad properties of HA, even though, as in most HA-grafted polymers, the detailed conformational effects of such substitutions, while crucial in the design or optimization of drug delivery systems, remain unknown. Here, the conformation, size, secondary structure, hydrogen bond network, and hydration features of lactosylated HA derivatives were evaluated by using multiple independent molecular dynamics simulations. This revealed subtle but nevertheless significant changes in the HA scaffold, establishing the density of grafting as the key parameter determining its properties.

Development and Characterization of a High-Affinity Selective Galectin-3 Mouse Tool Compound in Mouse Models of Cancer

The interest in galectin-3 as a drug target in the cancer and fibrosis space has grown during the past few years with several new classes of compounds being developed. The first orally available galectin-3 inhibitor, GB1211 (h-galectin-3 Kd = 0.025 μM), is currently in phase 2 clinical trials. Due to structural differences between human and mouse galectin-3 a significant reduction in mouse galectin-3 affinity is observed for most highly potent human galectin-3 inhibitors including GB1211 (m-galectin-3 Kd = 0.77 μM). Pharmacokinetic experiments in mouse dosing GB1211 up to 100 mg/kg results in free plasma levels below m-galectin-3 Kd, which is not comparable to the data observed in humans. To better support translation into clinical studies, a new improved mouse galectin-3 tool compound, GB2095, was developed. Dosing this new compound in in vivo syngeneic mouse models of cancer resulted in reduction of the growth of breast and melanoma cancers.

Central role of Galectin-3 at the cross-roads of cardiac inflammation and fibrosis: Implications for heart failure and transplantation

Cardiac inflammation and fibrosis are central pathogenic mechanisms leading to heart failure. Transplantation is still the treatment of choice for many patients undergoing end-stage heart failure who remain symptomatic despite optimal medical therapy. In spite of considerable progress, the molecular mechanisms linking inflammation, fibrosis and heart failure remain poorly understood. Galectin-3 (GAL3), a chimera-type member of the galectin family, has emerged as a critical mediator implicated in cardiac inflammatory, vascular and fibrotic processes through modulation of different cellular compartments including monocytes and macrophages, fibroblasts, endothelial cells and vascular smooth muscle cells via glycan-dependent or independent mechanisms. GAL3-driven circuits may hierarchically amplify cytokine production and function, immune cell activation and fibrosis cascades, influencing a wide range of cardiovascular disorders. Thus, GAL3 emerges as a potential therapeutic target to counteract aberrant inflammation and fibrosis during heart failure and a potential biomarker of heart failure and clinical outcome of heart transplantation.

Immunotherapy for Head and Neck Squamous Cell Carcinoma: Present and Future Approaches and Challenges

Despite significant progress and improving outcomes in the management of head and neck squamous cell carcinoma (HNSCC), there are few effective treatment options for patients with recurrent or metastatic head and neck squamous cell carcinoma. The advent of immune checkpoint inhibitors has changed the treatment algorithm of head and neck squamous cell carcinoma and are approved in the frontline setting for recurrent and metastatic (R/M) head and neck squamous cell carcinomas. Although promising for some patients, most patients with R/M HNSCC do not derive clinical benefit from currently approved checkpoint inhibitors. Many studies are underway to identify the patient population that would benefit the most from immunotherapy as well as postimmunotherapy treatment failures, including novel combinations of immunomodulatory therapies. In this review, we summarize the clinical development of all major clinical trials of immunotherapy in HNSCC.

c-MET and the immunological landscape of cancer: novel therapeutic strategies for enhanced anti-tumor immunity

Cellular mesenchymal-epithelial transition factor (c-MET), also known as hepatocyte growth factor receptor (HGFR), is a crucial receptor tyrosine kinase implicated in various solid tumors, including lung, breast, and liver cancers. The concomitant expression of c-MET and PD-L1 in tumors, such as hepatocellular carcinoma, highlights their prognostic significance and connection to therapeutic resistance. Cancer-associated fibroblasts and mesenchymal stromal cells produce hepatocyte growth factor (HGF), activating c-MET signaling in tumor cells and myeloid-derived suppressor cells (MDSC). This activation leads to metabolic reprogramming and increased activity of enzymes like glutaminase (GLS), indoleamine 2,3-dioxygenase (IDO), and arginase 1 (ARG1), depleting essential amino acids in the tumor microenvironment that are vital for effector immune cell function. This review highlights the interplay between tumor cells and myeloid-derived suppressor cells (MDSCs) that create an immunosuppressive environment while providing targets for c-MET-focused immunotherapy. It emphasizes the clinical implications of c-MET inhibition on the behavior of immune cells such as neutrophils, macrophages, T cells, and NK cells. It explores the potential of c-MET antagonism combined with immunotherapeutic strategies to enhance cancer treatment paradigms. This review also discusses the innovative cancer immunotherapies targeting c-MET, including chimeric antigen receptor (CAR) therapies, monoclonal antibodies, and antibody-drug conjugates, while encouraging the development of a comprehensive strategy that simultaneously tackles immune evasion and enhances anti-tumor efficacy further to improve the clinical prognoses for patients with c-MET-positive malignancies. Despite the challenges and variability in efficacy across different cancer subtypes, continued research into the molecular mechanisms and the development of innovative therapeutic strategies will be crucial.

Targeting Galectin-1 Overcomes Paclitaxel Resistance in Esophageal Squamous Cell Carcinoma

Resistance to paclitaxel poses a major obstacle in esophageal squamous cell carcinoma (ESCC) treatment. A better understanding of the mechanisms underlying paclitaxel resistance could help identify prognostic biomarkers and improved therapeutic strategies. In this study, we established a patient-derived xenograft model of acquired paclitaxel resistance and used RNA sequencing to identify galectin-1, encoded by LGALS1, as a key mediator of resistance. Integrative analysis of clinical data and physiological studies indicated that serum galectin-1 levels were elevated in resistant patients and correlated with treatment outcomes before and during taxane therapy. Importantly, exposing cells to serum from resistant patients resulted in increased paclitaxel resistance compared to serum from sensitive patients, which was closely associated with galectin-1 concentrations in the serum. The specific clearance of galectin-1 from resistant patient serum significantly restored paclitaxel sensitivity, and inhibiting galectin-1, through knockdown or the pharmacologic inhibitor OTX008, increased sensitivity to paclitaxel. Galectin-1 inhibition reduced the activity of β-catenin, thereby inhibiting stem cell properties induced by the Wnt/β-catenin pathway. Furthermore, galectin-1 regulated MDR1 transcription through increased nuclear accumulation of β-catenin, thus increasing resistance to paclitaxel. Combining OTX008 with clinical taxane formulations effectively reversed paclitaxel resistance in vitro and in vivo. Elevated galectin-1 levels thus serve as an indicator of response to paclitaxel therapy in ESCC, offering a therapeutic intervention strategy to overcome drug resistance. Significance: Galectin-1 is a key mediator of paclitaxel resistance in esophageal squamous cell carcinoma that can be targeted to improve taxane efficacy, suggesting broad therapeutic potential for treating various cancer types.

Sugar mimics and their probable binding sites: design and synthesis of thiazole linked coumarin-piperazine hybrids as galectin-1 inhibitors

Sugar mimics are valuable tools in medicinal chemistry, offering the potential to overcome the limitations of carbohydrate inhibitors, such as poor pharmacokinetics and non-selectivity. In our continued efforts to develop heterocyclic galectin-1 inhibitors, we report the synthesis and characterization of thiazole-linked coumarin piperazine hybrids (10a-10i) as Gal-1 inhibitors. The compounds were characterized using 1H NMR, 13C NMR and HRMS. Among the synthesized molecules, four compounds demonstrated significant inhibitory activity, with more than 50% inhibition observed at a concentration of 20 μM in a Gal-1 enzyme assay. Fluorescence spectroscopy was further utilized to elucidate the binding constant for the synthesized compounds. 10g exhibited the highest affinity for Gal-1, with a binding constant (K a) of 9.8 × 104 M-1. To elucidate the mode of binding, we performed extensive computational analyses with 10g, including 1.2 μs all-atom molecular dynamics simulations coupled with a robust machine learning tool. Our findings indicate that 10g binds to the carbohydrate binding site of Gal-1, with the coumarin moiety playing a key role in binding interactions. Additionally, our study underscores the limitations of relying solely on docking scores for conformational selection and highlights the critical importance of performing multiple MD replicas to gain accurate insights.

Design and Synthesis of Dual Galectin-3 and EGFR Inhibitors Against Liver Fibrosis

Liver fibrosis, mainly arising from chronic viral or metabolic liver diseases, is a significant global health concern. There is currently only one FDA-approved drug (Resmetirom) in the market to combat liver fibrosis. Both galectin-3 and epidermal growth factor receptor (EGFR) play important roles in liver fibrosis, while galectin-3 may interact with EGFR. Galectin-3 inhibitors, typically lactose or galactose derivatives may inhibit liver fibrosis. We hypothesized that targeting both galectin-3 and EGFR may have better effect against liver fibrosis. Here, EGFR inhibitor erlotinib was used in a series of designed galectin-3 inhibitors after hybridization with the pharmacophore structure in reported galectin-3 inhibitors to impede hepatic stellate cells (HSCs) activation by a typical method of click chemistry. Bioactivity test results showed that compound 29 suppressed TGF-β-induced upregulation of fibrotic markers (α-SMA, fibronectin-1, and collagen I). The preferred compound 29 displayed better binding to galectin-3 (KD=52.29 μM) and EGFR protein (KD=3.31 μM) by SPR assay. Further docking studies were performed to clarify the possible binding mode of compound 29 with galectin-3 and EGFR. Taken together, these results suggested that compound 29 could be a potential dual galectin-3 and EGFR inhibitor as leading compound for anti-liver fibrosis new drug development.

A C-type lectin from Bothrops jararacussu venom reprograms endothelial cell biology

Snake venoms are intricate mixtures of enzymes and bioactive factors that induce a range of detrimental effects in afflicted hosts. Certain Viperids, including Bothrops jararacussu, harbor C-type lectins (CTLs) known for their modulation of a variety of host cellular responses. In this study, we isolated and purified BjcuL, a CTL from B. jararacussu venom and investigated its impact on endothelial cell behavior, contrasting it with human galectin-1 (Gal-1), a prototype member of the galectin family with shared β-galactoside-binding activity. We found that BjcuL binds to human dermal microvascular endothelial cells (HMECs) in a concentration- and carbohydrate-dependent fashion and reprograms the function of these cells, favoring a pro-inflammatory and pro-coagulant endothelial phenotype. In light of the quest for universal antagonists capable of mitigating the harmful consequences of snake venoms, BjcuL emerges as a promising target to be blocked in order to regulate pathological endothelial cell responses.

Galectin-9 activates host immune response and improve immunoprotection of Onychostoma macrolepis against Aeromonas hydrophila infection

Galectin-9 (Gal-9) belongs to a family of the glycan-binding proteins (GBPs) and is known to restrict bacterial activity via interacting with pathogen associated molecular pattern (PAMPs). However, the underlying immune mechanism of endogenous Gal-9 on fish against bacterial infection is still unclear. In this study, effects of Gal-9 from Onychostoma macrolepis (OmGal-9) on expression of immune-related genes were measured by HEK293T. The immune response of O. macrolepis with OmGal-9 overexpression to Aeromonas hydrophila (A. hydrophila) infection (1.65 × 108 CFU/mL) was evaluated by tissue bacterial load, fish survival rate and transcriptome analysis. The results showed that OmGal-9 displayed a punctate distribution in the nucleus and cytoplasm of HEK293T cells. Compared to cells transfected with the empty vector (EV group), recombinant plasmid pEGFP-Gal9 treatment (Gal9 group) significantly down-regulated the expression of immune-related genes TNFα, STAT3, MyD88, LCK, and p52 of HEK293T cells stimulated with LPS at 24 h, while up-regulated IκBα and caspase-1 (P < 0.05). The activities of catalase (CAT), superoxide dismutase (SOD), the total antioxidant capacity (T-AOC), alkaline phosphatase (AKP), acid phosphatase (ACP), and lysozyme (LZM) of O. macrolepis were significantly increased on 7 days in Gal9 group compared to EV group (P < 0.05). The bacterial load of liver, spleen, and kidney of O. macrolepis infected with A. hydrophila in Gal9 group at 24 h was significantly lower than that in EV group (P < 0.05), and the survival rate had increased from 15 % to 35 %. A comparative transcriptome analysis between the Gal9 and EV group identified 305 differentially expressed genes (DEGs). The analysis showed that OmGal-9 might play an important regulatory role in glycolysis/gluconeogenesis, fatty acid degradation, and ascorbate and aldarate metabolism. Moreover, the immune-related DEGs were predominantly enriched in eleven pathways, with the most important three of them being linked to innate immunity: NOD-like, C-type lectin and Toll-like receptor signaling pathway. Taking together, OmGal-9 can enhance the resistance of fish to bacterial diseases by improving immune system function and activating immune-related pathways.

The prognostic utility of galectin-3 in patients undergoing cardiac surgery: a scoping review

OBJECTIVE

To review the utility of galectin-3 (Gal-3) as a biomarker for postoperative adverse outcomes in patients undergoing cardiac surgery.

METHOD

This review was conducted in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Electronic database search was conducted in October 2023. Studies that measured pre- and/or postoperative plasma Gal-3 levels in adult patients undergoing cardiac surgery were included. Primary outcomes included postoperative morbidity and mortality.

RESULTS

Out of 391 studies screened, eight studies met the inclusion criteria. Two of the three studies showed that preoperative plasma levels of Gal-3 were associated with acute kidney injury (AKI) after cardiac surgery. Two of the three studies reported a significant increase in preoperative Gal-3 levels in patients who developed postoperative atrial fibrillation (POAF). The addition of Gal-3 to the EuroSCORE II model was found to statistically improve the prediction of both AKI and POAF. Three of the five studies suggested that Gal-3 levels can predict postoperative mortality. Finally, one study suggested that lower preoperative Gal-3 levels was associated with a higher likelihood of achieving left ventricular reverse remodeling (LVRR) after surgery.

CONCLUSIONS

Gal-3 may play a promising role in predicting adverse outcomes in patients undergoing cardiac surgery. The addition of Gal-3 to clinical risk prediction scores may improve their discriminatory power in this group of patients. Future studies are warranted to justify its incorporation into routine clinical practice.

Gold-siRNA supraclusters enhance the anti-tumor immune response of stereotactic ablative radiotherapy at primary and metastatic tumors

Strategies to enhance the anti-tumor immune response of stereotactic ablative radiotherapy (SABR) at primary tumors and abscopal sites are under intensive investigation. Here we report a metabolizable binary supracluster (BSCgal) that combines gold nanoclusters as radiosensitizing adjuvants with small interfering RNA (siRNA) targeting the immunosuppressive mediator galectin-1 (Gal-1). BSCgal comprises reversibly crosslinked cationic gold nanoclusters and siRNA complexes in a polymer matrix that biodegrades over weeks, facilitating clearance (90.3% in vivo clearance at 4 weeks) to reduce toxicity. The particle size well above the renal filtration threshold facilitates passive delivery to tumors. Using mouse models of head and neck cancer, we show that BSCgal augments the radiodynamic and immunotherapeutic effects of SABR at the primary and metastatic tumors by promoting tumor-inhibitory leukocytes, upregulating cytotoxic granzyme B and reducing immunosuppressive cell populations. It outperforms SABR plus Gal-1 antagonists, chemoradiation drug cisplatin or PD-1 inhibitor. This work presents a translatable strategy to converge focal radiosensitization with targeted immune checkpoint silencing for personalized radioimmunotherapy.

PD-1 immunology in the kidneys: a growing relationship

In recent years, knowledge regarding immune regulation has expanded rapidly, and major advancements have been made in immunotherapy for immune-associated disorders, particularly cancer. The programmed cell death 1 (PD-1) pathway is a cornerstone in immune regulation. It comprises PD-1 and its ligands mediating immune tolerance mechanisms and immune homeostasis. Accumulating evidence demonstrates that the PD-1 axis has a crucial immunosuppressive role in the tumor microenvironment and autoimmune diseases. PD-1 receptors and ligands on immune cells and renal parenchymal cells aid in maintaining immunological homeostasis in the kidneys. Here, we present a comprehensive review of PD-1 immunology in various kidney disorders, including renal cell carcinoma, glomerulonephritis, kidney transplantation, renal aging, and renal immune-related adverse events secondary to PD-1 immunotherapy.

Harnessing the Power of Sugar-Based Nanoparticles: A Drug-Free Approach to Enhance Immune Checkpoint Inhibition against Glioblastoma and Pancreatic Cancer

Cancer cells have a high demand for sugars and express diverse carbohydrate receptors, offering opportunities to improve delivery with multivalent glycopolymer materials. However, effectively delivering glycopolymers to tumors while inhibiting cancer cell activity, altering cellular metabolism, and reversing tumor-associated macrophage (TAM) polarization to overcome immunosuppression remains a challenging area of research due to the lack of reagents capable of simultaneously achieving these objectives. Here, the glycopolymer-like condensed nanoparticle (∼60 nm) was developed by a one-pot carbonization reaction with a single precursor, promoting multivalent interactions for the galactose-related receptors of the M2 macrophage (TAM) and thereby regulating the STAT3/NF-κB pathways. The subsequently induced M2-to-M1 transition was increased with the condensed level of glycopolymer-like nanoparticles. We found that the activation of the glycopolymer-like condensed galactose (CG) nanoparticles influenced monocarboxylate transporter 4 (MCT-4) function, which caused inhibited lactate efflux (similar to inhibitor effects) from cancer cells. Upon internalization via galactose-related endocytosis, CG NPs induced cellular reactive oxygen species (ROS), leading to dual functionalities of cancer cell death and M2-to-M1 macrophage polarization, thereby reducing the tumor's acidic microenvironment and immunosuppression. Blocking the nanoparticle-MCT-4 interaction with antibodies reduced their toxicity in glioblastoma (GBM) and affected macrophage polarization. In orthotopic GBM and pancreatic cancer models, the nanoparticles remodeled the tumor microenvironment from "cold" to "hot", enhancing the efficacy of anti-PD-L1/anti-PD-1 therapy by promoting macrophage polarization and activating cytotoxic T lymphocytes (CTLs) and dendritic cells (DCs). These findings suggest that glycopolymer-like nanoparticles hold promise as a galactose-elicited adjuvant for precise immunotherapy, particularly in targeting hard-to-treat cancers.

Wong Z, Karali CS, Sirinukunwattana K, Ryou H, Norfo R, Cheng Q, Carrelha J, Ren Z, Thongjuea S, Rathinam VA, Krishnan A, Royston D, Rabinovich GA, Mead AJ, Psaila B. A proinflammatory stem cell niche drives myelofibrosis through a targetable galectin-1 axis

Myeloproliferative neoplasms are stem cell-driven cancers associated with a large burden of morbidity and mortality. Most patients present with early-stage disease, but a substantial proportion progress to myelofibrosis or secondary leukemia, advanced cancers with a poor prognosis and high symptom burden. Currently, it remains difficult to predict progression, and therapies that reliably prevent or reverse fibrosis are lacking. A major bottleneck to the discovery of disease-modifying therapies has been an incomplete understanding of the interplay between perturbed cellular and molecular states. Several cell types have individually been implicated, but a comprehensive analysis of myelofibrotic bone marrow is lacking. We therefore mapped the cross-talk between bone marrow cell types in myelofibrotic bone marrow. We found that inflammation and fibrosis are orchestrated by a "quartet" of immune and stromal cell lineages, with basophils and mast cells creating a TNF signaling hub, communicating with megakaryocytes, mesenchymal stromal cells, and proinflammatory fibroblasts. We identified the β-galactoside-binding protein galectin-1 as a biomarker of progression to myelofibrosis and poor survival in multiple patient cohorts and as a promising therapeutic target, with reduced myeloproliferation and fibrosis in vitro and in vivo and improved survival after galectin-1 inhibition. In human bone marrow organoids, TNF increased galectin-1 expression, suggesting a feedback loop wherein the proinflammatory myeloproliferative neoplasm clone creates a self-reinforcing niche, fueling progression to advanced disease. This study provides a resource for studying hematopoietic cell-niche interactions, with relevance for cancer-associated inflammation and disorders of tissue fibrosis.

Small lectin ligands as a basis for applications in glycoscience and glycomedicine

Glycan recognition by lectins mediates important biological events. This Tutorial Review aims to introduce lectin-ligand interactions and show how these molecular recognition events inspire innovations such as: (i) glycomimetic ligands; (ii) multivalent ligand agonists/antagonists; (iii) ligands for precision delivery of therapies to cells, where therapies include vaccines, siRNA and LYTACs (iv) development of diagnostics. A small number of case studies are selected to demonstrate principles for development of new ligands for applications inspired by knowledge of natural glycan ligand structure and function.

Lectin-Based Approaches to Analyze the Role of Glycans and Their Clinical Application in Disease

Lectin-based approaches remain a valuable tool for analyzing glycosylation, especially when detecting cancer-related changes. Certain glycans function as platforms for cell communication, signal transduction, and adhesion. Therefore, the functions of glycans are important considerations for clinical aspects, such as cancer, infection, and immunity. Considering that the three-dimensional structure and multivalency of glycans are important factors for their function, their binding characteristics toward lectins provide vital information. Glycans and lectins are inextricably linked, and studies on lectins have also led to research on the roles of glycans. The applications of lectins are not limited to analysis but can also be used as drug delivery tools. Moreover, mammalian lectins are potential therapeutic targets because certain lectins change their expression in cancer, and lectin regulation subsequently regulates several molecules with glycans. Herein, we review lectin-based approaches for analyzing the role of glycans and their clinical applications in diseases, as well as our recent results.

CUREs for high-level Galectin-3 expression

Galectins are a large and diverse protein family defined by the presence of a carbohydrate recognition domain (CRD) that binds β-galactosides. They play important roles in early development, tissue regeneration, immune homeostasis, pathogen recognition, and cancer. In many cases, studies that examine galectin biology and the effect of manipulating galectins are aided by, or require the ability to express and purify, specific members of the galectin family. In many cases, E. coli is employed as a heterologous expression system, and galectin expression is induced with isopropyl β-galactoside (IPTG). Here, we show that galectin-3 recognizes IPTG with micromolar affinity and that as IPTG induces expression, newly synthesized galectin can bind and sequester cytosolic IPTG, potentially repressing further expression. To circumvent this putative inhibitory feedback loop, we utilized an autoinduction protocol that lacks IPTG, leading to significantly increased yields of galectin-3. Much of this work was done within the context of a course-based undergraduate research experience, indicating the ease and reproducibility of the resulting expression and purification protocols.

The role of proliferating stem-like plasma cells in relapsed or refractory multiple myeloma: Insights from single-cell RNA sequencing and proteomic analysis

The management and comprehension of relapsed or refractory multiple myeloma (RRMM) continues to pose a significant challenge. By integrating single-cell RNA sequencing (scRNA-seq) data of 15 patients with plasma cell disorders (PCDs) and proteomic data obtained from mass spectrometry-based analysis of CD138+ plasma cells (PCs) from 144 PCDs patients, we identified a state of malignant PCs characterized by high stemness score and increased proliferation originating from RRMM. This state has been designated as proliferating stem-like plasma cells (PSPCs). NUCKS1 was identified as the gene marker representing the stemness of PSPCs. Comparison of differentially expressed genes among various PC states revealed a significant elevation in LGALS1 expression in PSPCs. Survival analysis on the MMRF CoMMpass dataset and GSE24080 dataset established LGALS1 as a gene associated with unfavourable prognostic implications for multiple myeloma. Ultimately, we discovered three specific ligand-receptor pairs within the midkine (MDK) signalling pathway network that play distinct roles in facilitating efficient cellular communication between PSPCs and the surrounding microenvironment cells. These insights have the potential to contribute to the understanding of molecular mechanism and the development of therapeutic strategies involving the application of stem-like cells in RRMM treatment.

Galectin-1 Attenuates PDGF-Mediated AKT Signaling in Retinal Pigment Epithelial Cells

Galectins have the potential to interact with transmembrane glycoproteins to modulate their functions. Since galectin-1 interacts with PDGF-Rβ, we analyzed the effect of galectin-1 on PDGF-BB-mediated AKT signaling in primary human retinal pigment epithelial (RPE) cells and galectin-1-deficient immortalized human RPE cells (LGALS1-/-/ARPE-19) following incubation with PDGF-BB and galectin-1. Expression and localization of galectin-1, PDGF-Rβ and pAKT were investigated using western blot analysis and immunohistochemical staining. Cell proliferation of RPE cells was analyzed using BrdU ELISA. Following treatment of human RPE cells with human recombinant (hr)-galectin-1 and PDGF-BB, an intense clustering of PDGF-Rβ and colocalization with galectin-1 were detected. By Western blot analysis and immunocytochemistry of human RPE cells, an enhanced PDGF-BB-mediated expression of pAKT was observed, which was substantially reduced by additional incubation with hr-galectin-1. Vice versa, in LGALS1-/-/ARPE-19 cells, the PDGF-BB-induced pAKT signal was enhanced compared to wild-type cells. Furthermore, a decreased expression of PDGF-Rβ in human RPE cells was observed after treatment with PDGF-BB and hr-galectin-1, while in untreated LGALS1-/-/ARPE-19 cells, its constitutive expression was increased. In addition, after treatment of RPE cells with hr-galectin-1, the PDGF-BB-induced proliferation was markedly reduced. In summary, galectin-1 has the distinct potential to reduce PDGF-mediated pAKT signaling and proliferation in human RPE cells-an effect that is most likely facilitated via a decreased expression of PDGF-Rβ.

CH-π Interactions Are Required for Human Galectin-3 Function

Glycan-binding proteins, or lectins, recognize distinct structural elements of polysaccharides, to mediate myriad biological functions. Targeting glycan-binding proteins involved in human disease has been challenging due to an incomplete understanding of the molecular mechanisms that govern protein-glycan interactions. Bioinformatics and structural studies of glycan-binding proteins indicate that aromatic residues with the potential for CH-π interactions are prevalent in glycan-binding sites. However, the contributions of these CH-π interactions to glycan binding and their relevance in downstream function remain unclear. An emblematic lectin, human galectin-3, recognizes lactose and N-acetyllactosamine-containing glycans by positioning the electropositive face of a galactose residue over the tryptophan 181 (W181) indole forming a CH-π interaction. We generated a suite of galectin-3 W181 variants to assess the importance of these CH-π interactions to glycan binding and function. As determined experimentally and further validated with computational modeling, variants with smaller or less electron-rich aromatic side chains (W181Y, W181F, W181H) or sterically similar but nonaromatic residues (W181M, W181R) showed poor or undetectable binding to lactose and attenuated ability to bind mucins or agglutinate red blood cells. The latter functions depend on multivalent binding, highlighting that weakened CH-π interactions cannot be overcome by avidity. Two galectin-3 variants with disrupted hydrogen bonding interactions (H158A and E184A) showed similarly impaired lactose binding. Molecular simulations demonstrate that all variants have decreased binding orientation stability relative to native galectin-3. Thus, W181 collaborates with the endogenous hydrogen bonding network to enhance binding affinity for lactose, and abrogation of these CH-π interactions is as deleterious as eliminating key hydrogen bonding interactions. These findings underscore the critical roles of CH-π interactions in carbohydrate binding and lectin function and will aid the development of novel lectin inhibitors.

Transcriptome-Wide, Unbiased Profiling of Ribonuclease Targeting Chimeras

Various approaches have been developed to target RNA and modulate its function with modes of action including binding and cleavage. Herein, we explored how small molecule binding is correlated with cleavage induced by heterobifunctional ribonuclease targeting chimeras (RiboTACs), where RNase L is recruited to cleave the bound RNA target, in a transcriptome-wide, unbiased fashion. Only a fraction of bound targets was cleaved by RNase L, induced by RiboTAC binding. Global analysis suggested that (i) cleaved targets generally form a region of stable structure that encompasses the small molecule binding site; (ii) cleaved targets have preferred RNase L cleavage sites nearby small molecule binding sites; (iii) RiboTACs facilitate a cellular interaction between cleaved targets and RNase L; and (iv) the expression level of the target influences the extent of cleavage observed. In one example, we converted a binder of LGALS1 (galectin-1) mRNA into a RiboTAC. In MDA-MB-231 cells, the binder had no effect on galectin-1 protein levels, while the RiboTAC cleaved LGALS1 mRNA, reduced galectin-1 protein abundance, and affected galectin-1-associated oncogenic cellular phenotypes. Using LGALS1, we further assessed additional factors including the length of the linker that tethers the two components of the RiboTAC, cellular uptake, and the RNase L-recruiting module on RiboTAC potency. Collectively, these studies may facilitate triangulation of factors to enable the design of RiboTACs.

Exploring galectin interactions with human milk oligosaccharides and blood group antigens identifies BGA6 as a functional galectin-4 ligand

Galectins (Gals), a family of multifunctional glycan-binding proteins, have been traditionally defined as β-galactoside binding lectins. However, certain members of this family have shown selective affinity toward specific glycan structures including human milk oligosaccharides (HMOs) and blood group antigens. In this work, we explored the affinity of human galectins (particularly Gal-1, -3, -4, -7, and -12) toward a panel of oligosaccharides including HMOs and blood group antigens using a complementary approach based on both experimental and computational techniques. While prototype Gal-1 and Gal-7 exhibited differential affinity for type I versus type II Lac/LacNAc residues and recognized fucosylated neutral glycans, chimera-type Gal-3 showed high binding affinity toward poly-LacNAc structures including LNnH and LNnO. Notably, the tandem-repeat human Gal-12 showed preferential recognition of 3-fucosylated glycans, a unique feature among members of the galectin family. Finally, Gal-4 presented a distinctive glycan-binding activity characterized by preferential recognition of specific blood group antigens, also validated by saturation transfer difference nuclear magnetic resonance experiments. Particularly, we identified oligosaccharide blood group A antigen tetraose 6 (BGA6) as a biologically relevant Gal-4 ligand, which specifically inhibited interleukin-6 secretion induced by this lectin on human peripheral blood mononuclear cells. These findings highlight unique determinants underlying specific recognition of HMOs and blood group antigens by human galectins, emphasizing the biological relevance of Gal-4-BGA6 interactions, with critical implications in the development and regulation of inflammatory responses.

Insecticidal action of mammalian galectin-1-transfected Arabidopsis thaliana

BACKGROUND

Galectins (GALs) are a family of mammalian sugar-binding proteins specific for β-galactosides. Our previous studies have shown that the larval development of the diamondback moth (Plutella xylostella) is significantly disturbed when fed with recombinant mammalian galectin 1 (GAL1) derived from Escherichia coli. To further explore its applicability, two GAL1-overexpressed Arabidopsis [GAL1-Arabidopsis (whole plant) and GAL1-Arabidopsis-vas (vascular bundle-specific)] lines were established for insecticidal activity and mechanism studies.

RESULTS

The expression level of GAL1 in transgenic Arabidopsis is 1-0.5% (GAL1-Arabidopsis) and 0.08-0.01% (GAL1-Arabidopsis-vas) of total leaf soluble protein. Survival, body weight, and food consumption significantly decreased in a time-dependent manner in P. xylostella larvae (with chewing mouthparts) fed on GAL1-Arabidopsis. The mortality of Kolla paulula (with piercing-sucking mouthparts and xylem feeder) fed on GAL1-Arabidopsis-vas was also significantly higher than that fed on wild-type Arabidopsis (WT-Arabidopsis), but was lower than that fed on GAL1-Arabidopsis. The histochemical structure and results of immunostaining suggested that the binding of GAL1 to the midgut epithelium of P. xylostella fed on GAL1-Arabidopsis was dose- and time-dependent. Ultrastructural studies further showed the disruption of microvilli, abnormalities in epithelial cells, and fragments of the peritrophic membrane (PM) in P. xylostella larvae fed on GAL1-Arabidopsis.

CONCLUSION

The insecticidal mechanism of GAL1 involves interference with PM integrity and suggests that GAL1 is a potential candidate for bioinsecticide development. © 2024 Society of Chemical Industry.

Emerging Roles of Galectin-3 in Pulmonary Diseases

Galectin-3 is a multifunctional protein that is involved in various physiological and pathological events. Emerging evidence suggests that galectin-3 also plays a critical role in the pathogenesis of pulmonary diseases. Galectin-3 can be produced and secreted by various cell types in the lungs, and the overexpression of galectin-3 has been found in acute lung injury/acute respiratory distress syndrome (ALI/ARDS), pulmonary hypertension (PH), pulmonary fibrosis diseases, lung cancer, lung infection, chronic obstructive pulmonary disease (COPD), and asthma. Galectin-3 exerts diverse effects on the inflammatory response, immune cell activation, fibrosis and tissue remodeling, and tumorigenesis in these pulmonary disorders, and genetic and pharmacologic modulation of galectin-3 has therapeutic effects on the treatment of pulmonary illnesses. In this review, we summarize the structure and function of galectin-3 and the underlying mechanisms of galectin-3 in pulmonary disease pathologies; we also discuss preclinical and clinical evidence regarding the therapeutic potential of galectin-3 inhibitors in these pulmonary disorders. Additionally, targeting galectin-3 may be a very promising therapeutic approach for the treatment of pulmonary diseases.

Metabolic profiling of galectin-1 and galectin-3: a cross-sectional, multi-omics, association study

OBJECTIVES

Experimental studies indicate a role for galectin-1 and galectin-3 in metabolic disease, but clinical evidence from larger populations is limited.

METHODS

We measured circulating levels of galectin-1 and galectin-3 in the Prospective investigation of Obesity, Energy and Metabolism (POEM) study, participants (n = 502, all aged 50 years) and characterized the individual association profiles with metabolic markers, including clinical measures, metabolomics, adipose tissue distribution (Imiomics) and proteomics.

RESULTS

Galectin-1 and galectin-3 were associated with fatty acids, lipoproteins and triglycerides including lipid measurements in the metabolomics analysis adjusted for body mass index (BMI). Galectin-1 was associated with several measurements of adiposity, insulin secretion and insulin sensitivity, while galectin-3 was associated with triglyceride-glucose index (TyG) and fasting insulin levels. Both galectins were associated with inflammatory pathways and fatty acid binding protein (FABP)4 and -5-regulated triglyceride metabolic pathways. Galectin-1 was also associated with several proteins related to adipose tissue differentiation.

CONCLUSIONS

The association profiles for galectin-1 and galectin-3 indicate overlapping metabolic effects in humans, while the distinctly different associations seen with fat mass, fat distribution, and adipose tissue differentiation markers may suggest a functional role of galectin-1 in obesity.

Different roles of the heterodimer architecture of galectin-4 in selective recognition of oligosaccharides and lipopolysaccharides having ABH antigens

The dimeric architecture of tandem-repeat type galectins, such as galectin-4 (Gal-4), modulates their biological activities, although the underlying molecular mechanisms have remained elusive. Emerging evidence show that tandem-repeat galectins play an important role in innate immunity by recognizing carbohydrate antigens present on the surface of certain pathogens, which very often mimic the structures of the human self-glycan antigens. Herein, we have analyzed the binding preferences of the C-domain of Gal-4 (Gal-4C) toward the ABH-carbohydrate histo-blood antigens with different core presentations and their recognition features have been rationalized by using a combined experimental approach including NMR, solid-phase and hemagglutination assays, and molecular modeling. The data show that Gal-4C prefers A over B antigens (two-fold in affinity), contrary to the N-domain (Gal-4N), although both domains share the same preference for the type-6 presentations. The behavior of the full-length Gal-4 (Gal-4FL) tandem-repeat form has been additionally scrutinized. Isothermal titration calorimetry and NMR data demonstrate that both domains within full-length Gal-4 bind to the histo-blood antigens independently of each other, with no communication between them. In this context, the heterodimeric architecture does not play any major role, apart from the complementary A and B antigen binding preferences. However, upon binding to a bacterial lipopolysaccharide containing a multivalent version of an H-antigen mimetic as O-antigen, the significance of the galectin architecture was revealed. Indeed, our data point to the linker peptide domain and the F-face of the C-domain as key elements that provide Gal-4 with the ability to cross-link multivalent ligands, beyond the glycan binding capacity of the dimer.

Vascular galectins in tumor angiogenesis and cancer immunity

Sustained tumor angiogenesis, i.e., the induction and maintenance of blood vessel growth by tumor cells, is one of the hallmarks of cancer. The vascularization of malignant tissues not only facilitates tumor growth and metastasis, but also contributes to immune evasion. Important players in all these processes are the endothelial cells which line the luminal side of blood vessel. In the tumor vasculature, these cells are actively involved in angiogenesis as well in the hampered recruitment of immune cells. This is the result of the abnormal tumor microenvironment which triggers both angiostimulatory and immune inhibitory gene expression profiles in endothelial cells. In recent years, it has become evident that galectins constitute a protein family that is expressed in the tumor endothelium. Moreover, several members of this glycan-binding protein family have been found to facilitate tumor angiogenesis and stimulate immune suppression. All this has identified galectins as potential therapeutic targets to simultaneously hamper tumor angiogenesis and alleviate immune suppression. The current review provides a brief introduction in the human galectin protein family. The current knowledge regarding the expression and regulation of galectins in endothelial cells is summarized. Furthermore, an overview of the role that endothelial galectins play in tumor angiogenesis and tumor immunomodulation is provided. Finally, some outstanding questions are discussed that should be addressed by future research efforts. This will help to fully understand the contribution of endothelial galectins to tumor progression and to exploit endothelial galectins for cancer therapy.

Intracellular galectin interactions in health and disease

In the galectin family, a group of lectins is united by their evolutionarily conserved carbohydrate recognition domains. These polypeptides play a role in various cellular processes and are implicated in disease mechanisms such as cancer, fibrosis, infection, and inflammation. Following synthesis in the cytosol, manifold interactions of galectins have been described both extracellularly and intracellularly. Extracellular galectins frequently engage with glycoproteins or glycolipids in a carbohydrate-dependent manner. Intracellularly, galectins bind to non-glycosylated proteins situated in distinct cellular compartments, each with multiple cellular functions. This diversity complicates attempts to form a comprehensive understanding of the role of galectin molecules within the cell. This review enumerates intracellular galectin interaction partners and outlines their involvement in cellular processes. The intricate connections between galectin functions and pathomechanisms are illustrated through discussions of intracellular galectin assemblies in immune and cancer cells. This underscores the imperative need to fully comprehend the interplay of galectins with the cellular machinery and to devise therapeutic strategies aimed at counteracting the establishment of galectin-based disease mechanisms.

Selection of Galectin-Binding Ligands from Synthetic Glycopeptide Libraries

Galectins, a class of carbohydrate-binding proteins, play a crucial role in various physiological and disease processes. Therefore, the identification of ligands that efficiently bind these proteins could potentially lead to the development of new therapeutic compounds. In this study, we present a method that involves screening synthetic click glycopeptide libraries to identify lectin-binding ligands with low micromolar affinity. Our methodology, initially optimized using Concanavalin A, was subsequently applied to identify binders for the therapeutically relevant galectin 1. Binding affinities were assessed using various methods and showed that the selected glycopeptides exhibited enhanced binding potency to the target lectins compared to the starting sugar moieties. This approach offers an alternative means of discovering galectin-binding ligands as well as other carbohydrate-binding proteins, which are considered important therapeutic targets.

ABO blood groups and galectins: Implications in transfusion medicine and innate immunity

ABO blood group antigens, which are complex carbohydrate moieties, and the first human polymorphisms identified, are critical in transfusion medicine and transplantation. Despite their discovery over a century ago, significant questions remain about the development of anti-ABO antibodies and the structural features of ABO antigens that cause hemolytic transfusion reactions. Anti-ABO antibodies develop naturally during the first few months of life, in contrast to other red blood cell (RBC) alloantibodies which form after allogeneic RBC exposure. Anti-ABO antibodies are the most common immune barrier to transfusion and transplantation, but the factors driving their formation are incompletely understood. Some studies suggest that microbes that express glycans similar in structure to the blood group antigens could play a role in anti-blood group antibody formation. While the role of these microbes in clinically relevant anti-blood group antibody formation remains to be defined, the presence of these microbes raises questions about how blood group-positive individuals protect themselves against blood group molecular mimicry. Recent studies suggest that galectins can bind and kill microbes that mimic blood group antigens, suggesting a unique host defense mechanism against microbial molecular mimicry. However, new models are needed to fully define the impact of microbes, galectins, or other factors on the development of clinically relevant naturally occurring anti-blood group antibodies.

Shaping hematopoietic cell ecosystems through galectin-glycan interactions

Hematopoiesis- the formation of blood cell components- continually replenishes the blood system during embryonic development and postnatal lifespans. This coordinated process requires the synchronized action of a broad range of cell surface associated proteins and soluble mediators, including growth factors, cytokines and lectins. Collectively, these mediators control cellular communication, signalling, commitment, proliferation, survival and differentiation. Here we discuss the role of galectins - an evolutionarily conserved family of glycan-binding proteins - in the establishment and dynamic remodelling of hematopoietic niches. We focus on the contribution of galectins to B and T lymphocyte development and selection, as well as studies highlighting the role of these proteins in myelopoiesis, with particular emphasis on erythropoiesis and megakaryopoiesis. Finally, we also highlight recent findings suggesting the role of galectin-1, a prototype member of this protein family, as a key pathogenic factor and therapeutic target in myelofibrosis. Through extracellular or intracellular mechanisms, galectins can influence the fate and function of distinct hematopoietic progenitors and fine-tune the final repertoire of blood cells, with critical implications in a wide range of physiologically vital processes including innate and adaptive immunity, immune tolerance programs, tissue repair, regeneration, angiogenesis, inflammation, coagulation and oxygen delivery. Additionally, positive or negative regulation of galectin-driven circuits may contribute to a broad range of blood cell disorders.

Glycosylation in the tumor immune response: the bitter side of sweetness

Glycosylation is the most structurally diverse form of post-translational modification (PTM) of proteins that affects a myriad of cellular processes. As a pivotal regulator of protein homeostasis, glycosylation notably impacts the function of proteins, spanning from protein localization and stability to protein-protein interactions. Aberrant glycosylation is a hallmark of cancer, and extensive studies have revealed the multifaceted roles of glycosylation in tumor growth, migration, invasion and immune escape Over the past decade, glycosylation has emerged as an immune regulator in the tumor microenvironment (TME). Here, we summarize the intricate interplay between glycosylation and the immune system documented in recent literature, which orchestrates the regulation of the tumor immune response through endogenous lectins, immune checkpoints and the extracellular matrix (ECM) in the TME. In addition, we discuss the latest progress in glycan-based cancer immunotherapy. This review provides a basic understanding of glycosylation in the tumor immune response and a theoretical framework for tumor immunotherapy.

A Quantitative Human Red Blood Cell Agglutination Assay for Characterisation of Galectin Inhibitors

Galectins are a family of beta-galactoside-binding proteins that are characterised by their carbohydrate recognition domain (CRD) and include galectin-1 and galectin-3. These galectins have been implicated in numerous diseases due to their pleiotropic nature, including cancer and fibrosis, with therapeutic inhibitors being clinically developed to block the CRD. One of the early methods developed to characterise these galectins was the hemagglutination of red blood cells. Although it is insightful, this approach has been hampered by a lack of sensitivity and accurate quantification of the agglutination observed. In this study, we aimed to validate a more precise and quantitative method to enable the further investigation of differences between galectins in respect to agglutination induction in different blood groups, as well as the characterisation of small molecule inhibitors. Quantification of hemagglutination was shown to be optimal using U-bottom plates imaged and analysed with FIJI ImageJ rather than flat-bottom plates read for absorbance on an optical density plate reader. Galectin-3-induced red blood cell agglutination efficacy increased significantly from blood group O to A to B. However, for both the galectin-1 monomer and concatemer, a more comparable effect was observed between blood group B and O, but with more potent effects than in blood group A. Inhibition assays for both galectin-3 and galectin-1 induced-hemagglutination were able to demonstrate clear concentration responses and expected selectivity profiles for a set of small-molecule glycomimetics, confirming the historical profiles obtained in biochemical binding and functional cellular assays.

Determining the Affinity and Kinetics of Small Molecule Inhibitors of Galectin-1 Using Surface Plasmon Resonance

The beta-galactoside-binding mammalian lectin galectin-1 can bind, via its carbohydrate recognition domain (CRD), to various cell surface glycoproteins and has been implicated in a range of cancers. As a consequence of binding to sugar residues on cell surface receptors, it has been shown to have a pleiotropic effect across many cell types and mechanisms, resulting in immune system modulation and cancer progression. As a result, it has started to become a therapeutic target for both small and large molecules. In previous studies, we used fluorescence polarization (FP) assays to determine KD values to screen and triage small molecule glycomimetics that bind to the galectin-1 CRD. In this study, surface plasmon resonance (SPR) was used to compare human and mouse galectin-1 affinity measures with FP, as SPR has not been applied for compound screening against this galectin. Binding affinities for a selection of mono- and di-saccharides covering a 1000-fold range correlated well between FP and SPR assay formats for both human and mouse galectin-1. It was shown that slower dissociation drove the increased affinity at human galectin-1, whilst faster association was responsible for the effects in mouse galectin-1. This study demonstrates that SPR is a sound alternative to FP for early drug discovery screening and determining affinity estimates. Consequently, it also allows association and dissociation constants to be measured in a high-throughput manner for small molecule galectin-1 inhibitors.

Highly accurate carbohydrate-binding site prediction with DeepGlycanSite

As the most abundant organic substances in nature, carbohydrates are essential for life. Understanding how carbohydrates regulate proteins in the physiological and pathological processes presents opportunities to address crucial biological problems and develop new therapeutics. However, the diversity and complexity of carbohydrates pose a challenge in experimentally identifying the sites where carbohydrates bind to and act on proteins. Here, we introduce a deep learning model, DeepGlycanSite, capable of accurately predicting carbohydrate-binding sites on a given protein structure. Incorporating geometric and evolutionary features of proteins into a deep equivariant graph neural network with the transformer architecture, DeepGlycanSite remarkably outperforms previous state-of-the-art methods and effectively predicts binding sites for diverse carbohydrates. Integrating with a mutagenesis study, DeepGlycanSite reveals the guanosine-5'-diphosphate-sugar-recognition site of an important G-protein coupled receptor. These findings demonstrate DeepGlycanSite is invaluable for carbohydrate-binding site prediction and could provide insights into molecular mechanisms underlying carbohydrate-regulation of therapeutically important proteins.

Discovery of the Selective and Orally Available Galectin-1 Inhibitor GB1908 as a Potential Treatment for Lung Cancer

We have previously described a new series of selective and orally available galectin-1 inhibitors resulting in the thiazole-containing glycomimetic GB1490. Here, we show that the introduction of polar substituents to the thiazole ring results in galectin-1-specific compounds with low nM affinities. X-ray structural analysis of a new ligand-galectin-1 complex shows changes in the binding mode and ligand-protein hydrogen bond interactions compared to the GB1490-galectin-1 complex. These new high affinity ligands were further optimized with respect to affinity and ADME properties resulting in the galectin-1-selective GB1908 (Kd galectin-1/3 0.057/6.0 μM). In vitro GB1908 inhibited galectin-1-induced apoptosis in Jurkat cells (IC50 = 850 nM). Pharmacokinetic experiments in mice revealed that a dose of 30 mg/kg b.i.d. results in free levels of GB1908 in plasma over galectin-1 Kd for 24 h. GB1908 dosed with this regimen reduced the growth of primary lung tumor LL/2 in a syngeneic mouse model.

Galectin-3 depletion tames pro-tumoural microglia and restrains cancer cells growth

Galectin-3 (Gal-3) is a multifunctional protein that plays a pivotal role in the initiation and progression of various central nervous system diseases, including cancer. Although the involvement of Gal-3 in tumour progression, resistance to treatment and immunosuppression has long been studied in different cancer types, mainly outside the central nervous system, its elevated expression in myeloid and glial cells underscores its profound impact on the brain's immune response. In this context, microglia and infiltrating macrophages, the predominant non-cancerous cells within the tumour microenvironment, play critical roles in establishing an immunosuppressive milieu in diverse brain tumours. Through the utilisation of primary cell cultures and immortalised microglial cell lines, we have elucidated the central role of Gal-3 in promoting cancer cell migration, invasion, and an immunosuppressive microglial phenotypic activation. Furthermore, employing two distinct in vivo models encompassing primary (glioblastoma) and secondary brain tumours (breast cancer brain metastasis), our histological and transcriptomic analysis show that Gal-3 depletion triggers a robust pro-inflammatory response within the tumour microenvironment, notably based on interferon-related pathways. Interestingly, this response is prominently observed in tumour-associated microglia and macrophages (TAMs), resulting in the suppression of cancer cells growth.

Mulberry Leaf Lipid Nanoparticles: a Naturally Targeted CRISPR/Cas9 Oral Delivery Platform for Alleviation of Colon Diseases

Oral treatment of colon diseases with the CRISPR/Cas9 system has been hampered by the lack of a safe and efficient delivery platform. Overexpressed CD98 plays a crucial role in the progression of ulcerative colitis (UC) and colitis-associated colorectal cancer (CAC). In this study, lipid nanoparticles (LNPs) derived from mulberry leaves are functionalized with Pluronic copolymers and optimized to deliver the CRISPR/Cas gene editing machinery for CD98 knockdown. The obtained LNPs possessed a hydrodynamic diameter of 267.2 nm, a narrow size distribution, and a negative surface charge (-25.6 mV). Incorporating Pluronic F127 into LNPs improved their stability in the gastrointestinal tract and facilitated their penetration through the colonic mucus barrier. The galactose end groups promoted endocytosis of the LNPs by macrophages via asialoglycoprotein receptor-mediated endocytosis, with a transfection efficiency of 2.2-fold higher than Lipofectamine 6000. The LNPs significantly decreased CD98 expression, down-regulated pro-inflammatory cytokines (TNF-α and IL-6), up-regulated anti-inflammatory factors (IL-10), and polarized macrophages to M2 phenotype. Oral administration of LNPs mitigated UC and CAC by alleviating inflammation, restoring the colonic barrier, and modulating intestinal microbiota. As the first oral CRISPR/Cas9 delivery LNP, this system offers a precise and efficient platform for the oral treatment of colon diseases.

Polysaccharide of sunflower (Helianthus annuus L.) stalk pith inhibits cancer proliferation and metastases via TNF-α pathway

The decoctions of sunflower (Helianthus annuus L. HAL) stalk pith have been used to treat advanced cancer, and polysaccharide of sunflower stalk pith (HSPP) was key ingredient of the decoctions. To forage specially structured HSPP with anti-tumor effects and to uncover its mechanisms of anticancer activity, syngeneic mouse model of lung carcinoma metastasis was established and the HSPP was found to contain long-chain fatty acid. Encouragingly, the mean survival of the polysaccharide group (47.3 ± 12.8 d) and its sub-fractions group HSPP-4 (50.7 ± 13.0 d) was significantly increased compared with control group (38.7 ± 12.7 d) or positive control group (41.8 ± 13.4 d), (n = 20, P < 0.01 vs. the control group or positive control group). Furthermore, the HSPP exerted inhibitory effects on the tumor cells' metastasis. Eventually, it is postulated that the polysaccharide could inhibit tumor proliferation and metastasis by reduction of TNF-α from the macrophage.

The role of galectins in mediating the adhesion of circulating cells to vascular endothelium

Vascular cell adhesion is a complex orchestration of events that commonly feature lectin-ligand interactions between circulating cells, such as immune, stem, and tumor cells, and endothelial cells (ECs) lining post-capillary venules. Characteristically, circulating cell adherence to the vasculature endothelium is initiated through interactions between surface sialo-fucosylated glycoprotein ligands and lectins, specifically platelet (P)- or endothelial (E)-selectin on ECs or between leukocyte (L)-selectin on circulating leukocytes and L-selectin ligands on ECs, culminating in circulating cell extravasation. This lectin-ligand interplay enables the migration of immune cells into specific tissue sites to help maintain effective immunosurveillance and inflammation control, the homing of stem cells to bone marrow or tissues in need of repair, and, unfortunately, in some cases, the dissemination of circulating tumor cells (CTCs) to distant metastatic sites. Interestingly, there is a growing body of evidence showing that the family of β-galactoside-binding lectins, known as galectins, can also play pivotal roles in the adhesion of circulating cells to the vascular endothelium. In this review, we present contemporary knowledge on the significant roles of host- and/or tumor-derived galectin (Gal)-3, -8, and -9 in facilitating the adhesion of circulating cells to the vascular endothelium either directly by acting as bridging molecules or indirectly by triggering signaling pathways to express adhesion molecules on ECs. We also explore strategies for interfering with galectin-mediated adhesion to attenuate inflammation or hinder the metastatic seeding of CTCs, which are often rich in galectins and/or their glycan ligands.

The diverse dependence of galectin-1 and -8 on multivalency for the modulation of FGFR1 endocytosis

Fibroblast growth factor receptor 1 (FGFR1) is a N-glycosylated cell surface receptor tyrosine kinase, which upon recognition of specific extracellular ligands, fibroblast growth factors (FGFs), initiates an intracellular signaling. FGFR1 signaling ensures homeostasis of cells by fine-tuning essential cellular processes, like differentiation, division, motility and death. FGFR1 activity is coordinated at multiple steps and unbalanced FGFR1 signaling contributes to developmental diseases and cancers. One of the crucial control mechanisms over FGFR1 signaling is receptor endocytosis, which allows for rapid targeting of FGF-activated FGFR1 to lysosomes for degradation and the signal termination. We have recently demonstrated that N-glycans of FGFR1 are recognized by a precise set of extracellular galectins, secreted and intracellular multivalent lectins implicated in a plethora of cellular processes and altered in immune responses and cancers. Specific galectins trigger FGFR1 clustering, resulting in activation of the receptor and in initiation of intracellular signaling cascades that shape the cell physiology. Although some of galectin family members emerged recently as key players in the clathrin-independent endocytosis of specific cargoes, their impact on endocytosis of FGFR1 was largely unknown.Here we assessed the contribution of extracellular galectins to the cellular uptake of FGFR1. We demonstrate that only galectin-1 induces internalization of FGFR1, whereas the majority of galectins predominantly inhibit endocytosis of the receptor. We focused on three representative galectins: galectin-1, -7 and -8 and we demonstrate that although all these galectins directly activate FGFR1 by the receptor crosslinking mechanism, they exert different effects on FGFR1 endocytosis. Galectin-1-mediated internalization of FGFR1 doesn't require galectin-1 multivalency and occurs via clathrin-mediated endocytosis, resembling in this way the uptake of FGF/FGFR1 complex. In contrast galectin-7 and -8 impede FGFR1 endocytosis, causing stabilization of the receptor on the cell surface and prolonged propagation of the signals. Furthermore, using protein engineering approaches we demonstrate that it is possible to modulate or even fully reverse the endocytic potential of galectins.

Patient-derived follicular lymphoma spheroids recapitulate lymph node signaling and immune profile uncovering galectin-9 as a novel immunotherapeutic target

Follicular lymphoma (FL), the most common indolent non-Hodgkin lymphoma, constitutes a paradigm of immune tumor microenvironment (TME) contribution to disease onset, progression, and heterogenous clinical outcome. Here we present the first FL-Patient Derived Lymphoma Spheroid (FL-PDLS), including fundamental immune actors and features of TME in FL lymph nodes (LNs). FL-PDLS is organized in disc-shaped 3D structures composed of proliferating B and T cells, together with macrophages with an intermediate M1/M2 phenotype. FL-PDLS recapitulates the most relevant B-cell transcriptional pathways present in FL-LN (proliferation, epigenetic regulation, mTOR, adaptive immune system, among others). The T cell compartment in the FL-PDLS preserves CD4 subsets (follicular helper, regulatory, and follicular regulatory), also encompassing the spectrum of activation/exhaustion phenotypes in CD4 and CD8 populations. Moreover, this system is suitable for chemo and immunotherapy testing, recapitulating results obtained in the clinic. FL-PDLS allowed uncovering that soluble galectin-9 limits rituximab, rituximab, plus nivolumab/TIM-3 antitumoral activities. Blocking galectin-9 improves rituximab efficacy, highlighting galectin-9 as a novel immunotherapeutic target in FL. In conclusion, FL-PDLS maintains the crosstalk between malignant B cells and the immune LN-TME and constitutes a robust and multiplexed pre-clinical tool to perform drug screening in a patient-derived system, advancing toward personalized therapeutic approaches.

Engagement of sialylated glycans with Siglec receptors on suppressive myeloid cells inhibits anticancer immunity via CCL2

The overexpression of sialic acids on glycans, called hypersialylation, is a common alteration found in cancer cells. Sialylated glycans can enhance immune evasion by interacting with sialic acid-binding immunoglobulin-like lectin (Siglec) receptors on tumor-infiltrating immune cells. Here, we investigated the effect of sialylated glycans and their interaction with Siglec receptors on myeloid-derived suppressor cells (MDSCs). We found that MDSCs derived from the blood of lung cancer patients and tumor-bearing mice strongly express inhibitory Siglec receptors and are highly sialylated. In murine cancer models of emergency myelopoiesis, Siglec-E knockout in myeloid cells resulted in prolonged survival and increased tumor infiltration of activated T cells. Targeting suppressive myeloid cells by blocking Siglec receptors or desialylation strongly reduced their suppressive potential. We further identified CCL2 as a mediator involved in T-cell suppression upon interaction between sialoglycans and Siglec receptors on MDSCs. Our results demonstrated that sialylated glycans inhibit anticancer immunity by modulating CCL2 expression.

A vascularized breast cancer spheroid platform for the ranked evaluation of tumor microenvironment-targeted drugs by light sheet fluorescence microscopy

Targeting the supportive tumor microenvironment (TME) is an approach of high interest in cancer drug development. However, assessing TME-targeted drug candidates presents a unique set of challenges. We develop a comprehensive screening platform that allows monitoring, quantifying, and ranking drug-induced effects in self-organizing, vascularized tumor spheroids (VTSs). The confrontation of four human-derived cell populations makes it possible to recreate and study complex changes in TME composition and cell-cell interaction. The platform is modular and adaptable for tumor entity or genetic manipulation. Treatment effects are recorded by light sheet fluorescence microscopy and translated by an advanced image analysis routine in processable multi-parametric datasets. The system proved to be robust, with strong interassay reliability. We demonstrate the platform's utility for evaluating TME-targeted antifibrotic and antiangiogenic drugs side-by-side. The platform's output enabled the differential evaluation of even closely related drug candidates according to projected therapeutic needs.

Bioactive Properties of Venoms Isolated from Whiptail Stingrays and the Search for Molecular Mechanisms and Targets

The venom-containing barb attached to their 'whip-like' tail provides stingrays a defensive mechanism for evading predators such as sharks. From human encounters, dermal stingray envenomation is characterized by intense pain often followed by tissue necrosis occurring over several days to weeks. The bioactive components in stingray venoms (SRVs) and their molecular targets and mechanisms that mediate these complex responses are not well understood. Given the utility of venom-derived proteins from other venomous species for biomedical and pharmaceutical applications, we set out to characterize the bioactivity of SRV extracts from three local species that belong to the Dasyatoidea 'whiptail' superfamily. Multiple cell-based assays were used to quantify and compare the in vitro effects of these SRVs on different cell lines. All three SRVs demonstrated concentration-dependent growth-inhibitory effects on three different human cell lines tested. In contrast, a mouse fibrosarcoma cell line was markedly resistant to all three SRVs, indicating the molecular target(s) for mediating the SRV effects are not expressed on these cells. The multifunctional SRV responses were characterized by an acute disruption of cell adhesion leading to apoptosis. These findings aim to guide future investigations of individual SRV proteins and their molecular targets for potential use in biomedical applications.

Galectins in epithelial-mesenchymal transition: roles and mechanisms contributing to tissue repair, fibrosis and cancer metastasis

Galectins are soluble glycan-binding proteins that interact with a wide range of glycoproteins and glycolipids and modulate a broad spectrum of physiological and pathological processes. The expression and subcellular localization of different galectins vary among tissues and cell types and change during processes of tissue repair, fibrosis and cancer where epithelial cells loss differentiation while acquiring migratory mesenchymal phenotypes. The epithelial-mesenchymal transition (EMT) that occurs in the context of these processes can include modifications of glycosylation patterns of glycolipids and glycoproteins affecting their interactions with galectins. Moreover, overexpression of certain galectins has been involved in the development and different outcomes of EMT. This review focuses on the roles and mechanisms of Galectin-1 (Gal-1), Gal-3, Gal-4, Gal-7 and Gal-8, which have been involved in physiologic and pathogenic EMT contexts.

Pectin: Health-promoting properties as a natural galectin-3 inhibitor

Galectin-3 has a variety of important pathophysiological significance in the human body. Much evidence shows that the abnormal expression of galectin-3 is related to the formation and development of many diseases. Pectin is mostly obtained from processed citrus fruits and apples and is a known natural inhibitor of galactin-3. A large number of peels produced each year are discarded, and it is necessary to recycle some of the economically valuable active compounds in these by-products to reduce resource waste and environmental pollution. By binding with galectin-3, pectin can directly reduce the expression level of galectin-3 on the one hand, and regulate the expression level of cytokines by regulating certain signaling pathways on the other hand, to achieve the effect of treating diseases. This paper begins by presenting an overview of the basic structure of pectin, subsequently followed by a description of the structure of galectin-3 and its detrimental impact on human health when expressed abnormally. The health effects of pectin as a galectin-3 inhibitor were then summarized from the perspectives of anticancer, anti-inflammatory, ameliorating fibrotic diseases, and anti-diabetes. Finally, the challenges and prospects of future research on pectin are presented, which provide important references for expanding the application of pectin in the pharmaceutical industry or developing functional dietary supplements.