Showing papers on "Galectin published in 2014"
TL;DR: There is potential for the development of acellular therapeutic interventions for autoimmune, inflammatory, and malignant diseases and tissue regeneration from cellular secretions derived from MSCs cultured under the appropriate conditions.
Abstract: The mesenchymal stem cell (MSC) is being broadly studied in clinical trials. Contrary to the early paradigm of cell replacement and differentiation as a therapeutic mechanism of action, evidence is mounting that the secretions of the cells are responsible for their therapeutic effects. These secretions include molecules and extracellular vesicles that have both local and distant effects. This review summarizes the up- and down-regulation of MSC anti-inflammatory, immune modulating, anti-tumor, and regenerative secretions resulting from different stimuli including: a) hypoxia, which increases the production of growth factors and anti-inflammatory molecules; b) pro-inflammatory stimuli that induce the secretion of immune modulating and anti-inflammatory factors; and c) 3 dimensional growth which up regulates the production of anti-cancer factors and anti-inflammatory molecules compared to monolayer culture. Finally we review in detail the most important factors present in conditioned medium of MSC that can be considered protagonists of MSC physiological effects including HGF, TGF-b, VEGF, TSG-6, PGE2 and galectins 1, and 9. We conclude that there is potential for the development of acellular therapeutic interventions for autoimmune, inflammatory, and malignant diseases and tissue regeneration from cellular secretions derived from MSCs cultured under the appropriate conditions.
469 citations
TL;DR: Current concepts how tumor-cell-derived glycans contribute to metastasis are discussed with the focus on three types of lectins: siglecs, galectins, and selectins.
Abstract: Malignant transformation of cells is associated with aberrant glycosylation presented on the cell-surface. Commonly observed changes in glycan structures during malignancy encompasses aberrant expression and glycosylation of mucins; abnormal branching of N-glycans; and increased presence of sialic acid on proteins and glycolipids. Accumulating evidence supports the notion that the presence of certain glycan structures correlates with cancer progression by affecting tumor cell invasiveness, ability to disseminate through the blood circulation and to metastasize in distant organs. During metastasis tumor cell-derived glycans enable binding to cells in their microenvironment including endothelium and blood constituents through glycan-binding receptors - lectins. In this review we will discuss current concepts how tumor cell-derived glycans contribute to metastasis with the focus on three types of lectins: siglecs, galectins and selectins. Siglecs are present on virtually all hematopoetic cells and usually negatively regulate immune responses. Galectins are mostly expressed by tumor cells and support tumor cell survival. Selectins are vascular adhesion receptors that promote tumor cell dissemination. All lectins facilitate interactions within the tumor microenvironment and thereby promote cancer progression. The identification of mechanisms how tumor glycans contribute to metastasis may help to improve diagnosis, prognosis and aid to develop clinical strategies to prevent metastasis.
305 citations
TL;DR: It is concluded that Gal3 functionally integrates carbohydrate specificity on cargo proteins with the capacity of GSLs to drive clathrin-independent plasma membrane bending as a first step of CLIC biogenesis.
Abstract: Several cell surface molecules including signalling receptors are internalized by clathrin-independent endocytosis. How this process is initiated, how cargo proteins are sorted and membranes are bent remains unknown. Here, we found that a carbohydrate-binding protein, galectin-3 (Gal3), triggered the glycosphingolipid (GSL)-dependent biogenesis of a morphologically distinct class of endocytic structures, termed clathrin-independent carriers (CLICs). Super-resolution and reconstitution studies showed that Gal3 required GSLs for clustering and membrane bending. Gal3 interacted with a defined set of cargo proteins. Cellular uptake of the CLIC cargo CD44 was dependent on Gal3, GSLs and branched N-glycosylation. Endocytosis of β1-integrin was also reliant on Gal3. Analysis of different galectins revealed a distinct profile of cargoes and uptake structures, suggesting the existence of different CLIC populations. We conclude that Gal3 functionally integrates carbohydrate specificity on cargo proteins with the capacity of GSLs to drive clathrin-independent plasma membrane bending as a first step of CLIC biogenesis.
243 citations
TL;DR: An up-to-date overview of available data on the role of galectin-1 in different molecular and biochemical pathways involved in human malignancies is provided.
186 citations
TL;DR: Galectin-3 seems to play a relevant role in orchestrating distinct cell events in tumor microenvironment and for this reason, it can be considered a target in tumor therapies.
Abstract: Galectin-3, the only chimera galectin found in vertebrates, is one of the best-studied galectins. It is expressed in several cell types and is involved in a broad range of physiological and pathological processes, such as cell adhesion, cell activation and chemoattraction, cell cycle, apoptosis and cell growth and differentiation. However, this molecule raises special interest due to its role in regulating cancer cell activities. Galectin-3 has high affinity for beta-1,6-N-acetylglucosamine branched glycans, which are formed by the action of the beta-1,6-N-acetylglucosaminyltransferase V (Mgat5). Mgat5-related changes in protein/lipid glycosylation on cell surface lead to alterations in the clustering of membrane proteins through lattice formation, resulting in functional advantages for tumor cells. Galectin-3 presence enhances migration and/or invasion of many tumors. Galectin-3-dependent clustering of integrins promotes ligand-induced integrin activation, leading to cell motility. Galectin-3 binding to mucin-1 increases transendothelial invasion, decreasing metastasis-free survival in an experimental metastasis model. Galectin-3 also affects endothelial cell behavior by regulating capillary tube formation. This lectin is found in the tumor stroma, suggesting a role for microenvironmental galectin-3 in tumor progression. Galectin-3 also seems to be involved in the recruitment of tumor-associated macrophages, possibly contributing to angiogenesis and tumor growth. This lectin can be a relevant factor in turning bone marrow in a sanctuary for leukemia cells, favoring resistance to therapy. Finally, galectin-3 seems to play a relevant role in orchestrating distinct cell events in tumor microenvironment and for this reason, it can be considered a target in tumor therapies. In conclusion, this review aims to describe the processes of tumor progression and metastasis involving extracellular galectin-3 and its expression and regulation.
167 citations
TL;DR: This review reflects on glycan–lectin interactions in the context of viral infection and antiviral immunity, and outlines how recent advances in the glycan-lectin field might be transformed into promising new approaches to antiviral therapy.
Abstract: Glycans are carbohydrate modifications typically found on proteins or lipids, and can act as ligands for glycan-binding proteins called lectins. Glycans and lectins play crucial roles in the function of cells and organs, and in the immune system of animals and humans. Viral pathogens use glycans and lectins that are encoded by their own or the host genome for their replication and spread. Recent advances in glycobiological research indicate that glycans and lectins mediate key interactions at the virus-host interface, controlling viral spread and/or activation of the immune system. This review reflects on glycan–lectin interactions in the context of viral infection and antiviral immunity. A short introduction illustrates the nature of glycans and lectins, and conveys the basic principles of their interactions. Subsequently, examples are discussed highlighting specific glycan–lectin interactions and how they affect the progress of viral infections, either benefiting the host or the virus. Moreover, glycan and lectin variability and their potential biological consequences are discussed. Finally, the review outlines how recent advances in the glycan–lectin field might be transformed into promising new approaches to antiviral therapy.
118 citations
TL;DR: Agonistic anti–4-1BB suppresses autoimmune and allergic inflammation via binding to Galectin-9, which facilitates 4-1 BB aggregation, signaling, and functional activity.
Abstract: Biologics to TNF family receptors are prime candidates for therapy of immune disease. Whereas recent studies have highlighted a requirement for Fcγ receptors in enabling the activity of CD40, TRAILR, and GITR when engaged by antibodies, other TNFR molecules may be controlled by additional mechanisms. Antibodies to 4-1BB (CD137) are currently in clinical trials and can both augment immunity in cancer and promote regulatory T cells that inhibit autoimmune disease. We found that the action of agonist anti–4-1BB in suppressing autoimmune and allergic inflammation was completely dependent on Galectin-9 (Gal-9). Gal-9 directly bound to 4-1BB, in a site distinct from the binding site of antibodies and the natural ligand of 4-1BB, and Gal-9 facilitated 4-1BB aggregation, signaling, and functional activity in T cells, dendritic cells, and natural killer cells. Conservation of the Gal-9 interaction in humans has important implications for effective clinical targeting of 4-1BB and possibly other TNFR superfamily molecules.
105 citations
TL;DR: Findings suggest a novel immunoinhibitory function for LGALS3BP that might be important for immune evasion of tumor cells during cancer progression, as well as novel targets for cancer immunomodulatory therapy.
88 citations
TL;DR: The meta-analysis suggests that this phenomenon may enable the potential use of PP13 in directing patient management near to or at the time of delivery, and suggests its therapeutic potential in preeclampsia.
Abstract: Galectins are glycan-binding proteins that regulate innate and adaptive immune responses, and some confer maternal-fetal immune tolerance in eutherian mammals. A chromosome 19 cluster of galectins has emerged in anthropoid primates, species with deep placentation and long gestation. Three of the five human cluster galectins are solely expressed in the placenta, where they may confer additional immunoregulatory functions to enable deep placentation. One of these is galectin-13, also known as Placental Protein 13 (PP13). It has a “jelly-roll” fold, carbohydrate-recognition domain and sugar-binding preference resembling to other mammalian galectins. PP13 is predominantly expressed by the syncytiotrophoblast and released from the placenta into the maternal circulation. Its ability to induce apoptosis of activated T cells in vitro, and to divert and kill T cells as well as macrophages in the maternal decidua in situ suggests important immune functions. Indeed, mutations in the promoter and an exon of LGALS13 presumably leading to altered or non-functional protein expression are associated with a higher frequency of preeclampsia and other obstetrical syndromes, which involve immune dysregulation. Moreover, decreased placental expression of PP13 and its low first trimester maternal serum concentrations are associated with elevated risk of preeclampsia. Indeed, PP13 turned to be a good early biomarker to assess maternal risk for the subsequent development of pregnancy complications caused by impaired placentation. Due to the ischemic placental stress in preterm preeclampsia, there is an increased trophoblastic shedding of PP13 immunopositive microvesicles starting in the second trimester, which leads to high maternal blood PP13 concentrations. Our meta-analysis suggests that this phenomenon may enable the potential use of PP13 in directing patient management near to or at the time of delivery. Recent findings on the beneficial effects of PP13 on decreasing blood pressure du
85 citations
TL;DR: In this paper, the authors showed that CPP-induced autophagy was also dependent on endocytosis as the process was significantly inhibited by methyl-β-cyclodextrin and dynasore, which suppress clathrin-dependent endocyte-dependent autophagousy.
75 citations
TL;DR: The evolutionary origins of the placental expression of Chr19 cluster galectin genes are revealed and the complex dysregulation of these genes in preeclampsia may alter immune tolerance mechanisms at the maternal-fetal interface.
TL;DR: The ways that the interactions of microbial glycans with host cell galectins positively and negatively regulate pathogen attachment, invasion, and survival, as well as regulate host responses that mitigate microbial pathogenesis are discussed.
Abstract: Microbe-host interactions are complex processes that are directly and indirectly regulated by a variety of factors, including microbe presentation of specific molecular signatures on the microbial surface, as well as host cell presentation of receptors that recognize these pathogen signatures. Cell surface glycans are one important class of microbial signatures that are recognized by a variety of host cell lectins. Host cell lectins that recognize microbial glycans include members of the galectin family of lectins that recognize specific glycan ligands on viruses, bacteria, fungi, and parasites. In this review, we will discuss the ways that the interactions of microbial glycans with host cell galectins positively and negatively regulate pathogen attachment, invasion, and survival, as well as regulate host responses that mitigate microbial pathogenesis.
TL;DR: This study identified and functionally characterized a galectin from the kuruma shrimp Marsupenaeus japonicus, which it is shown participates in clearance of bacteria from circulation, and thereby contributes to the shrimp’s immune defense against infectious challenge.
Abstract: Galectins are a lectin family characterized by a conserved sequence motif in the carbohydrate recognition domain, which preferential binds to galactosyl moieties. However, few studies about the biological roles of galectins in invertebrates have been reported except for the galectin (CvGal1) from the eastern oyster Crassostrea virginica. Furthermore, galectins have been described in only a few crustacean species, and no functional studies have been reported so far. In this study, we identified and functionally characterized a galectin from the kuruma shrimp Marsupenaeus japonicus, which we designated MjGal. Upon Vibrio anguillarum challenge, expression of MjGal was up-regulated mostly in hemocytes and hepatopancreas, and the protein bound to both Gram-positive and Gram-negative bacteria through the recognition of lipoteichoic acid (LTA) or lipopolysaccharide (LPS), respectively. By also binding to the shrimp hemocyte surface, MjGal functions as an opsonin for microbial pathogens, promoting their phagocytosis. Further, as shown by RNA interference, MjGal participates in clearance of bacteria from circulation, and thereby contributes to the shrimp’s immune defense against infectious challenge. Elucidation of functional and mechanistic aspects of shrimp immunity will enable the development of novel strategies for intervention in infectious diseases currently affecting the shrimp farming industry worldwide.
TL;DR: Key structural features revealed include galectin-3's demonstration of a binding mode towards gangliosides distinct from that to the lacto/neolacto-glycosphingolipids, with its capacity for recognising the core β-galactoside region being challenged when the core oligosaccharide epitope of ganglio-series glycosphingalipids (GM3) is embedded within particular higher-molecular-weight glycans.
TL;DR: An increasing number of studies indicate that these proteins can also alter tumor progression through their interaction with intracellular ligands and call for a change in the basic assumptions, or paradigms, concerning the activity of galectins in cancer.
Abstract: Dysregulation of galectin expression is frequently observed in cancer tissues. Such an abnormal expression pattern often correlates with aggressiveness and relapse in many types of cancer. Because galectins have the ability to modulate functions that are important for cell survival, migration and metastasis, they also represent attractive targets for cancer therapy. This has been well-exploited for extracellular galectins, which bind glycoconjugates expressed on the surface of cancer cells. Although the existence of intracellular functions of galectins has been known for many years, an increasing number of studies indicate that these proteins can also alter tumor progression through their interaction with intracellular ligands. In fact, in some instances, the interactions of galectins with their intracellular ligands seem to occur independently of their carbohydrate recognition domain. Such findings call for a change in the basic assumptions, or paradigms, concerning the activity of galectins in cancer and may force us to revisit our strategies to develop galectin antagonists for the treatment of cancer.
TL;DR: Increased circulation of galectins -2, -4 and -8 in cancer patients contributes substantially to the increased circulation of G-CSF, IL-6 and MCP-1 by interaction with the blood vascular endothelium.
Abstract: Circulating galectins -2, -4 and -8 in cancer patients make important contributions to the increased circulation of several cytokines and chemokines that promote angiogenesis and metastasis
TL;DR: Increased galectin-9 protein levels in the endothelium of different tumors, including carcinomas of the lung, liver, breast and kidney are shown, showing that endothelial cells regulate the expression and splicing of LGALS9 during angiogenesis.
TL;DR: Galectins can play important roles inside the cells in response to infection by intracellular bacteria, and they are expressed by barrier tissues as well as immune cells, and can function both inside and outside the cells.
TL;DR: The current knowledge of galectin-1 and -9 in endothelial cell biology and angiogenesis is reviewed and the contribution of both galectins to other processes that involve the endothelium, including inflammation and coagulation is described.
Abstract: The growth of new blood vessels out of the pre-existing vasculature, i.e., angiogenesis, is executed by endothelial cells that normally form the inner lining of blood vessels. During angiogenesis, these cells exert different activities which require interactions with other cells and with the extracellular environment. It has become evident that this frequently involves galectins since the members of this protein family facilitate interactions between cells and/or glycoproteins via carbohydrate binding. In addition, they can regulate intracellular processes like signaling and splicing via noncarbohydrate interactions. We have previously reported on the role of galectin-1 and -9 in endothelial cell function. Here, we review the current knowledge of these two galectins in endothelial cell biology and angiogenesis. In addition, we describe the contribution of both galectins to other processes that involve the endothelium, including inflammation and coagulation. Finally, we discuss the challenges for future research in order to better understand how this “sweet” couple exerts its multifunctional activities within the vasculature.
TL;DR: The mapping of seven members of this family of adhesion/growth-regulatory proteins in human cartilage specimens revealed gene transcription and protein presence in cultured OA chondrocytes, especially for galectin-1, galECTin-3 and galectIn-8, and direct further research toward examining cellular effects of these proteins (alone or in combination) on chondROcytes and remodeling of the chONDrocyte glycophenotype.
Abstract: The apparent connection of galectin-3 to chondrocyte survival and osteoarthritis-like cartilage modifications in animal models provided incentive for the mapping of seven members of this family of adhesion/growth-regulatory proteins in human cartilage specimens. Starting with work in vitro, RT-qPCR analyses and immunocytochemistry revealed gene transcription and protein presence in cultured OA chondrocytes, especially for galectin-1, galectin-3 and galectin-8. Immunohistochemistry in clinical specimens with mild and severe cartilage degeneration detected galectins in chondrocytes-with upregulation, especially of galectin-1 in areas of severe degeneration-accompanied by α2,6-sialylation in the pericellular matrix. Given the possibility for additive/antagonistic activities between galectins, these results direct further research toward examining cellular effects of (1) these proteins (alone or in combination) on chondrocytes and (2) remodeling of the chondrocyte glycophenotype.
TL;DR: It is found that exogenous Gal-3 slightly delays, while prolonging tyrosine phosphorylation of extracellular signal-regulated kinase 1/2 in HeLa cells through a calcium-sensitive and PKC-dependent signaling pathway.
Abstract: The presence and level of circulating galectin-3 (Gal-3), a member of the galectin family, is associated with diverse diseases ranging from heart failure, immune disorders to cancer metastasis and serves as a biomarker of diagnosis and treatment response. However, the mechanisms by which exogenous Gal-3 affects pathobiology events remain elusive. In the current study, we found that exogenous Gal-3 slightly delays, while prolonging tyrosine phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) in HeLa cells through a calcium-sensitive and PKC-dependent signaling pathway. The activation was dependent on the sugar-binding properties of Gal-3, since the antagonist lactose could inhibit it. The sugar-binding motif of Gal-3 was required for the activation of ERK1/2. The activation of ERK1/2 was necessary for the initiation and induction of cell migration associated with the phosphorylation of paxillin. All the results presented in this study suggest a novel calcium-sensitive and PKC-dependent pathway through which circulating Gal-3 promotes cell migration and activating the ERK1/2. Taken together, the data depicted here propose a biological function and a target for the diseases' associated circulating Gal-3.
18 Apr 2014
TL;DR: It is shown that CPP-induced autophagy was also dependent on endocytosis as the process was significantly inhibited by methyl-β-cyclodextrin and dynasore, which suppress clathrin-dependent endocyTosis and agents that affect endosome/lysosome maturation and function, such as bafilomycin A1, also significantly affected C PP-induced tubulovesicular autophagosome formation.
Abstract: Calcium phosphate precipitates (CPPs) form complexes with DNA, which enter cells via endocytosis. Under this condition CPPs induce autophagy via the canonic autophagy machinery. Here we showed that CPP-induced autophagy was also dependent on endocytosis as the process was significantly inhibited by methyl-β-cyclodextrin and dynasore, which suppress clathrin-dependent endocytosis. Consistently, CPP treatment triggered the formation of filipin-positive intracellular vesicles whose membranes are rich in cholesterol. Unexpectedly, these vesicles were also positive for galectin 3, suggesting that they were damaged and the membrane glycans became accessible to galectins to bind. Endosome damage was caused by endocytosis of CPPs and was reversed by calcium chelators or by endocytosis inhibitors. Notably, CPP-induced LC3-positive autophagosomes were colocalized with galectin 3, ubiquitin, and p62/SQSTM1. Inhibition of galectin 3 reduced p62 puncta and autophagosome formation. Knockdown of p62 additionally inhibited the colocalization of autophagosomes with galectins. Furthermore, most of the galectin 3-positive vesicles were colocalized with Rab7 or LAMP1. Agents that affect endosome/lysosome maturation and function, such as bafilomycin A1, also significantly affected CPP-induced tubulovesicular autophagosome formation. These findings thus indicate that endocytosed CPPs caused endosome damage and recruitment of galectins, particularly at the later endosome stage, which led to the interaction of the autophagosomal membranes with the damaged endosome in the presence of p62. Background: Relationship of autophagosomes with endosomal vesicles varies in different conditions. Results: Calcium phosphate precipitates required endocytosis to induce autophagy, caused endosome damage, and recruited autophagosomes to the damaged vesicles. Conclusion: Damaged endosomes can be targeted by autophagosomes. Significance: Autophagy may play a role in endosomal homeostasis.
TL;DR: A novel role for gal-8 is described in the regulation of vascular and lymphatic angiogenesis and evidence of its critical implications in tumor biology is provided, including cell adhesion and migration, which collectively demonstrate the multi-functionality of this complex lectin.
Abstract: Fil: Troncoso, Maria Fernanda. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto de Quimica y Fisico-Quimica Biologicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquimica. Instituto de Quimica y Fisico-Quimica Biologicas; Argentina
TL;DR: RHco-gal-m modulated goat monocytes and T cell function in different patterns, and induced apoptosis in T cells, but not significantly in monocytes.
Abstract: Background: Monocytes and T cells are two major subpopulations of peripheral blood mononuclear cells (PBMC) and play an essential role in the innate and adaptive immune systems. Different members of the galectin family show multiple and distinct regulatory effects on different cell types. Previous studies have demonstrated that the galectin from Haemonchus contortus (Hco-gal-m) performed immunomodulatory effects on goat PBMC, however, which subpopulation of PBMC is the primary target of Hco-gal-m and whether the immune modulations share the same mechanism remain unclear. Methods: In this study, the developmental expression of Hco-gal-m was analyzed by RT-PCR and Western blot analysis. The distribution of Hco-gal-m in adult worm was detected by an immunohistochemical test. The binding activity of the recombinant Hco-gal-m (rHco-gal-m) on goat monocytes and T cells were assessed by flow cytometry. The immunomodulatory effects of Hco-gal-m on cytokine secretion, cell activation and apoptosis were observed by co-incubation of rHco-gal-m with goat monocytes and T cells. Results: Hco-gal-m was expressed in L4 as well as adult worms and predominantly localized at the internal surface of the worm guts. rHco-gal-m could bind to both monocytes and T cells. The engagement of rHco-gal-m decreased the production of IL-6, IL-10 and TNF-α in T cells, however, it significantly increased the secretion of IL-10 in monocytes. After rHco-gal-m exposure, the expression of MHC-II on monocytes and that of CD25 on T cells were restricted. Consequently, T cell proliferations were potently inhibited by rHco-gal-m. In addition, rHco-gal-m induced apoptosis in T cells, but not significantly in monocytes.
TL;DR: It is shown that different members of the galectin family can selectively regulate the release of angiogenic molecules by human platelets and its selective blockade may lead to the development of therapeutic strategies for angiogenesis-related diseases.
Abstract: Platelets contribute to vessel formation through the release of angiogenesis-modulating factors stored in their α-granules. Galectins, a family of lectins that bind β-galactoside residues, are up-regulated in inflammatory and cancerous tissues, trigger platelet activation and mediate vascularization processes. Here we aimed to elucidate whether the release of platelet-derived proangiogenic molecules could represent an alternative mechanism through which galectins promote neovascularization. We show that different members of the galectin family can selectively regulate the release of angiogenic molecules by human platelets. Whereas Galectin (Gal)-1, -3, and -8 triggered vascular endothelial growth factor (VEGF) release, only Gal-8 induced endostatin secretion. Release of VEGF induced by Gal-8 was partially prevented by COX-1, PKC, p38 and Src kinases inhibitors, whereas Gal-1-induced VEGF secretion was inhibited by PKC and ERK blockade, and Gal-3 triggered VEGF release selectively through a PKC-dependent pathway. Regarding endostatin, Gal-8 failed to stimulate its release in the presence of PKC, Src and ERK inhibitors, whereas aspirin or p38 inhibitor had no effect on endostatin release. Despite VEGF or endostatin secretion, platelet releasates generated by stimulation with each galectin stimulated angiogenic responses in vitro including endothelial cell proliferation and tubulogenesis. The platelet angiogenic activity was independent of VEGF and was attributed to the concerted action of other proangiogenic molecules distinctly released by each galectin. Thus, secretion of platelet-derived angiogenic molecules may represent an alternative mechanism by which galectins promote angiogenic responses and its selective blockade may lead to the development of therapeutic strategies for angiogenesis-related diseases.
TL;DR: These glycosylation-dependent lectin-receptor interactions can link tumor hypoxia to EC signaling and control tumor sensitivity to anti-angiogenic treatment.
Abstract: Abnormal glycosylation is a typical hallmark of the transition from healthy to neoplastic tissues. Although the importance of glycans and glycan-binding proteins in cancer-related processes such as tumor cell adhesion, migration, metastasis and immune escape has been largely appreciated, our awareness of the impact of lectin-glycan recognition in tumor vascularization is relatively new. Regulated glycosylation can influence vascular biology by controlling trafficking, endocytosis and signaling of endothelial cell (EC) receptors including vascular endothelial growth factor receptors, platelet EC adhesion molecule, Notch and integrins. In addition, glycans may control angiogenesis by regulating migration of endothelial tip cells and influencing EC survival and vascular permeability. Recent evidence indicated that changes in the EC surface glycome may also serve "on-and-off" switches that control galectin binding to signaling receptors by displaying or masking-specific glycan epitopes. These glycosylation-dependent lectin-receptor interactions can link tumor hypoxia to EC signaling and control tumor sensitivity to anti-angiogenic treatment.
TL;DR: The present review summarizes the current knowledge regarding the role galectins in tumor angiogenesis focussing on the endothelial galectin, i.e., gal-1/-3/-8/-9.
Abstract: The expansion of solid tumors depends on the continuous ingrowth of new blood vessels out of pre-existing capillaries. Consequently, tumor neovascularization or tumor angiogenesis is considered a hallmark of cancer and an attractive target for cancer therapy. Tumor angiogenesis is mainly carried out by endothelial cells (EC), i.e., the cells lining the luminal vessel wall. These cells have to take on different functional activities in order to successfully make new tumor blood vessels. In the last decade it has become apparent that galectins are important regulators of tumor angiogenesis. In the present review we summarize the current knowledge regarding the role galectins in tumor angiogenesis focussing on the endothelial galectins, i.e., gal-1/-3/-8/-9.
TL;DR: It is found that GM-CT-01 boosts cytotoxicity of CD8+ TIL and their IFN-γ secretion in a dose-dependent manner and pave the way for investigating the potential benefit of this galectin antagonist in patients with cancer, alone or combined with cancer vaccination, in order to correct in vivo impaired functions of TIL.
Abstract: PURPOSE: Several galectins are released by tumor cells and macrophages and accumulate in the tumor microenvironment. Galectin-1 and -3 were found to bind to glycosylated receptors at the surface of tumor-infiltrating lymphocytes (TIL), forming glycoprotein-galectin lattices that could reduce the motility and therefore the functionality of surface molecules. In contrast to blood T cells, human TIL show defective IFN-γ secretion upon ex vivo stimulation. We have previously shown that extracellular galectin-3 participates in the impairment of TIL functions. Indeed, disruption of glycoprotein-galectin-3 lattices using anti-galectin-3 antibodies, or N-acetyllactosamine as a competing sugar, boosted cytokine secretion by TIL. Here we have tested a clinical grade galectin antagonist: GM-CT-01, a galactomannan obtained from guar gum reported to be safe in more than 50 cancer patients. EXPERIMENTAL DESIGN: TIL were isolated from human tumor ascites, treated for 2-20 h with galectin antagonists and tested for function. RESULTS: We found that GM-CT-01 boosts cytotoxicity of CD8+ TIL and their IFN-γ secretion in a dose-dependent manner. Treating TIL obtained from patients with various cancers, during a few hours, resulted in an increased IFN-γ secretion in up to 80% of the samples. CONCLUSIONS: These observations pave the way for investigating the potential benefit of this galectin antagonist in cancer patients, alone or combined with cancer vaccination, in order to correct in vivo impaired functions of TIL.
TL;DR: Investigation of the roles of galectins in neuroinflammation promise to provide a better understanding of the mechanism of this process and lead to new therapeutic approaches.
Abstract: Galectins, β-galactoside-binding lectins, play multiple roles in the regulation of immune and inflammatory responses. The major galectins expressed in the CNS are galectins 1, 3, 4, 8, and 9. Under normal physiological conditions, galectins maintain CNS homeostasis by participating in neuronal myelination, neuronal stem cell proliferation, and apical vesicle transport in neuronal cells. In neuronal diseases and different experimental neuroinflammatory disease models, galectins may serve as extracellular mediators or intracellular regulators in controlling the inflammatory response or conferring the remodeling capacity in damaged CNS tissues. In general, galectins 1 and 9 attenuate experimental autoimmune encephalomyelitis (a model of multiple sclerosis), while galectin-3 promotes inflammation in this model. In brain ischemic lesions, both galectins 1 and 3 are induced to help neuronal regeneration. The expression of galectin-1 is required for astrocyte-derived neurotrophic factor secretion, and recombinant galectin-1 promotes neuronal regeneration. Galectin-3 promotes microglial cell proliferation and attenuates ischemic damage and neuronal apoptosis after cerebral ischemia. In amyotrophic lateral sclerosis models, galectin-3 is deleterious to neuroregeneration, while intramuscular administration of oxidized galectin-1 can improve neuromuscular disorders. In axotomy and Wallerian degeneration, galectin-3 helps phagocytosis of macrophages to clear degenerate myelin in the injured PNS or CNS. Thus, galectins are important modulators participating in homeostasis of the CNS and neuroinflammation. Continued investigations of the roles of galectins in neuroinflammation promise to provide a better understanding of the mechanism of this process and lead to new therapeutic approaches.
TL;DR: This review summarizes the current knowledge of the signaling pathways activated by galectins, their glycan dependence and the cellular compartment where they become activated and are biologically relevant.
Abstract: Galectins control cell behavior by acting on different signaling pathways. Most of the biological activities ascribed to these molecules rely upon recognition of extracellular glycoconjugates and establishment of multivalente interactions, which trigger adaptive biological responses. However, galectins are also detected within the cell in different compartments, where their regulatory functions still remain poorly understood. A deeper understanding of the entire galectin signalosome and its impact in cell behavior is therefore essential in order to delineate new strategies to specifically manipulate both galectin expression and function. This review summarizes our current knowledge of the signaling pathways activated by galectins, their glycan dependence and the cellular compartment where they become activated and are biologically relevant.