On the role of galectin-3 in cancer apoptosis

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.

Galectin-3 and prohibitin 1 are autoantigens in IgG4-related cholangitis without clear-cut protective effects against toxic bile acids

Background and aims

IgG4-related cholangitis (IRC) is the hepatobiliary manifestation of IgG4-related disease, a systemic B cell-driven fibro-inflammatory disorder. Four autoantigens have recently been described in IgG4-RD: annexin A11, galectin-3, laminin 511-E8, and prohibitin 1. We have previously reported a protective role of annexin A11 and laminin 511-E8 in human cholangiocytes against toxic bile acids. Here, we explored the potentially protective role of the carbohydrate-binding lectin galectin-3 and the scaffold proteins prohibitins 1 and 2.

Methods

Anti-galectin-3, anti-prohibitin 1 and 2 autoantibody positivity in IRC and healthy and disease (primary sclerosing cholangitis (PSC)) control sera was assessed by ELISA/liquid chromatography-tandem mass spectrometry (LC-MS/MS). Human H69 cholangiocytes were subjected to short hairpin RNA (shRNA) knockdown targeting galectin-3 (LGALS3), prohibitin 1 (PHB1), and prohibitin 2 (PHB2). H69 cholangiocytes were also exposed to recombinant galectin-3, the inhibitor GB1107, recombinant prohibitin 1, and the pan-prohibitin inhibitor rocaglamide. Protection against bile acid toxicity was assessed by intracellular pH (pHi) measurements using BCECF-AM, 22,23-3H-glycochenodeoxycholic acid (3H-GCDC) influx, and GCDC-induced apoptosis using Caspase-3/7 assays.

Results

Anti-galectin-3 autoantibodies were detected in 13.5% of individuals with IRC but not in PSC. Knockdown of LGALS3 and galectin-3 inhibition with GB1107 did not affect pHi, whereas recombinant galectin-3 incubation lowered pHi. LGALS3 knockdown increased GCDC-influx but not GCDC-induced apoptosis. GB1107 reduced GCDC-influx and GCDC-induced apoptosis. Recombinant galectin-3 tended to decrease GCDC-influx and GCDC-induced apoptosis. Anti-prohibitin 1 autoantibodies were detected in 61.5% and 35.7% of individuals with IRC and PSC, respectively. Knockdown of PHB1, combined PHB1/2 KD, treatment with rocaglamide, and recombinant prohibitin 1 all lowered pHi. Knockdown of PHB1, PHB2, or combined PHB1/2 did not alter GCDC-influx, yet knockdown of PHB1 increased GCDC-induced apoptosis. Conversely, rocaglamide reduced GCDC-influx but did not attenuate GCDC-induced apoptosis. Recombinant prohibitin 1 did not affect GCDC-influx or GCDC-induced apoptosis. Finally, anti-galectin-3 and anti-prohibitin 1 autoantibody pretreatment did not lead to increased GCDC-influx.

Conclusions

A subset of individuals with IRC have autoantibodies against galectin-3 and prohibitin 1. Gene-specific knockdown, pharmacological inhibition, and recombinant protein substitution did not clearly disclose a protective role of these autoantigens in human cholangiocytes against toxic bile acids. The involvement of these autoantibodies in processes surpassing epithelial secretion remains to be elucidated.

Modified pectin with anticancer activity in breast cancer: A systematic review

Breast cancer is the most commonly diagnosed cancer among women worldwide. The current pharmacological treatments for breast cancer have numerous adverse effects and are not always effective. Recently, the anticancer activity of modified pectins (MPs) against various types of cancers, including breast cancer, has been investigated. This systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) model, including scientific articles from the last 22 years that measured the anticancer activity of MPs on breast cancer. The articles were searched in four databases with the terms: "modified pectin" and "breast cancer". Nine articles were included, five in vitro and four mixed (in vitro and in vivo). Different models and methods by which anticancer activity was measured were analyzed. All the studies reported positive results in both cell lines and in vivo murine models of breast cancer. The extracted data suggest a positive effect and provide mechanistic evidence of MPs in the treatment of breast cancer. However, as limited number of studies were included, further in vivo studies are required to obtain more conclusive preclinical evidence.

The Role of Galectin-3 in Retinal Degeneration and Other Ocular Diseases: A Potential Novel Biomarker and Therapeutic Target

Galectin-3 is the most studied member of the Galectin family, with a large range of mediation in biological activities such as cell growth, proliferation, apoptosis, differentiation, cell adhesion, and tissue repair, as well as in pathological processes such as inflammation, tissue fibrosis, and angiogenesis. As is known to all, inflammation, aberrant cell apoptosis, and neovascularization are the main pathophysiological processes in retinal degeneration and many ocular diseases. Therefore, the review aims to conclude the role of Gal3 in the retinal degeneration of various diseases as well as the occurrence and development of the diseases and discuss its molecular mechanisms according to research in systemic diseases. At the same time, we summarized the predictive role of Gal3 as a biomarker and the clinical application of its inhibitors to discuss the possibility of Gal3 as a novel target for the treatment of ocular diseases.

Galectin-3's Complex Interactions in Pancreatic Ductal Adenocarcinoma: From Cellular Signaling to Therapeutic Potential

Galectin-3 (Gal-3) plays a multifaceted role in the development, progression, and prognosis of pancreatic ductal adenocarcinoma (PDAC). This review offers a comprehensive examination of its expression in PDAC, its interaction with various immune cells, signaling pathways, effects on apoptosis, and therapeutic resistance. Additionally, the prognostic significance of serum levels of Gal-3 is discussed, providing insights into its potential utilization as a biomarker. Critical analysis is also extended to the inhibitors of Gal-3 and their potential therapeutic applications in PDAC, offering new avenues for targeted treatments. The intricate nature of Gal-3's role in PDAC reveals a complex landscape that demands a nuanced understanding for potential therapeutic interventions and monitoring.

Discovery of N-Arylsulfonyl-Indole-2-Carboxamide Derivatives as Galectin-3 and Galectin-8 C-Terminal Domain Inhibitors

Both galectin-3 and galectin-8 are involved in cell adhesion, migration, apoptosis, angiogenesis, and inflammatory processes by recognizing galactose-containing glycoproteins. Inhibiting galectin-3/8 activities is a potential treatment for cancer and tissue fibrosis. Herein, a series of novel N-arylsulfonyl-5-aryloxy-indole-2-carboxamide derivatives was disclosed as dual inhibitors toward galectin-3 and galectin-8 C-terminal domain with Kd values of low micromolar level (Cpd53, gal-3: Kd= 4.12 μM, gal-8C: Kd= 6.04 μM; Cpd57, gal-3: Kd= 12.8 μM, gal-8C: Kd= 2.06 μM), which are the most potent and selective noncarbohydrate-based inhibitors toward gal-3/8 isoforms to date. The molecular docking investigations suggested that the unique amino acids Arg144 in galectin-3 and Ser213 in galectin-8C could contribute to their potency and selectivity. The scratch wound assay demonstrated that Cpd53 and Cpd57 were able to inhibit the MRC-5 lung fibroblast cells migration as well. This class of inhibitors could serve as a new starting point for further discovering structurally distinct gal-3 and gal-8C inhibitors to be used in cancer and tissue fibrosis treatment.

Glycomimetics for the inhibition and modulation of lectins

Carbohydrates are essential mediators of many processes in health and disease. They regulate self-/non-self- discrimination, are key elements of cellular communication, cancer, infection and inflammation, and determine protein folding, function and life-times. Moreover, they are integral to the cellular envelope for microorganisms and participate in biofilm formation. These diverse functions of carbohydrates are mediated by carbohydrate-binding proteins, lectins, and the more the knowledge about the biology of these proteins is advancing, the more interfering with carbohydrate recognition becomes a viable option for the development of novel therapeutics. In this respect, small molecules mimicking this recognition process become more and more available either as tools for fostering our basic understanding of glycobiology or as therapeutics. In this review, we outline the general design principles of glycomimetic inhibitors (Section 2). This section is then followed by highlighting three approaches to interfere with lectin function, i.e. with carbohydrate-derived glycomimetics (Section 3.1), novel glycomimetic scaffolds (Section 3.2) and allosteric modulators (Section 3.3). We summarize recent advances in design and application of glycomimetics for various classes of lectins of mammalian, viral and bacterial origin. Besides highlighting design principles in general, we showcase defined cases in which glycomimetics have been advanced to clinical trials or marketed. Additionally, emerging applications of glycomimetics for targeted protein degradation and targeted delivery purposes are reviewed in Section 4.

Different types of fruit intake and colorectal cancer risk: A meta-analysis of observational studies

BACKGROUND

Multiple studies investigating the relationship between intake of different types of fruit and colorectal cancer (CRC) risk have yielded inconsistent results.

AIM

To perform a meta-analysis of existing studies to assess the association between the intake of different kinds of fruit and the incidence of CRC.

METHODS

We searched online literature databases including PubMed, Embase, WOS, and Cochrane Library for relevant articles available up to August 2022. With data extracted from observational studies, odds ratios (ORs) with 95% confidence intervals (CIs) were assessed using random-effects models. A funnel plot and Egger’s test were used to determine publication bias. Furthermore, subgroup analysis and dose-response analysis were performed. All analyses were conducted using R (version 4.1.3).

RESULTS

Twenty-four eligible studies involving 1068158 participants were included in this review. The meta-analysis showed that compared to a low intake, a higher intake of citrus, apples, watermelon, and kiwi reduced the risk of CRC by 9% [OR (95%CI) = 0.91 (0.85-0.97)], 25% [OR (95%CI) = 0.75 (0.66-0.85)], 26% [OR (95%CI) = 0.74 (0.58-0.94)], 13% [OR (95%CI) = 0.87 (0.78-0.96)], respectively. No significant association was observed between the intake of other types of fruit and the risk of CRC. In the dose-response analysis, a nonlinear association was found [R (95%CI) = -0.0031 (-0.0047 to -0.0014)] between citrus intake and CRC risk (P < 0.001), with the risk minimized around 120 g/d (OR = 0.85), while no significant dose-response correlation was observed after continued increase in intake.

CONCLUSION

We found that a higher intake of citrus, apples, watermelon, and kiwi was negatively associated with the risk of CRC, while the intake of other types of fruits were not significantly associated with CRC. Citrus intake showed a non-linear dose-response relationship with the risk of CRC. This meta-analysis provides further evidence that a higher intake of specific types of fruit is effective in preventing the occurrence of CRC.

Development of Galectin-3 Targeting Drugs for Therapeutic Applications in Various Diseases

Galectin-3 (Gal3) is one of the most studied members of the galectin family that mediate various biological processes such as growth regulation, immune function, cancer metastasis, and apoptosis. Since Gal3 is pro-inflammatory, it is involved in many diseases that are associated with chronic inflammation such as cancer, organ fibrosis, and type 2 diabetes. As a multifunctional protein involved in multiple pathways of many diseases, Gal3 has generated significant interest in pharmaceutical industries. As a result, several Gal3-targeting therapeutic drugs are being developed to address unmet medical needs. Based on the PubMed search of Gal3 to date (1987-2023), here, we briefly describe its structure, carbohydrate-binding properties, endogenous ligands, and roles in various diseases. We also discuss its potential antagonists that are currently being investigated clinically or pre-clinically by the public and private companies. The updated knowledge on Gal3 function in various diseases could initiate new clinical or pre-clinical investigations to test therapeutic strategies, and some of these strategies could be successful and recognized as novel therapeutics for unmet medical needs.

Atomic-Scale View of Protein-PEG Interactions that Redirect the Thermal Unfolding Pathway of PEGylated Human Galectin-3

PEGylation is a promising approach to address the central challenge of applying biologics, i.e., lack of protein stability in the demanding environment of the human body. Wider application is hindered by lack of atomic level understanding of protein-PEG interactions, preventing design of conjugates with predicted properties. We deployed an integrative structural and biophysical approach to address this critical challenge with the PEGylated carbohydrate recognition domain of human galectin-3 (Gal3C), a lectin essential for cell adhesion and potential biologic. PEGylation dramatically increased Gal3C thermal stability, forming a stable intermediate and redirecting its unfolding pathway. Structural details revealed by NMR pointed to a potential role of PEG localization facilitated by charged residues. Replacing these residues subtly altered the protein-PEG interface and thermal unfolding behavior, providing insight into rationally designing conjugates while preserving PEGylation benefits.

The pleiotropic role of galectin-3 in melanoma progression: Unraveling the enigma

Melanoma is a highly aggressive skin cancer with poor outcomes associated with distant metastasis. Intrinsic properties of melanoma cells alongside the crosstalk between melanoma cells and surrounding microenvironment determine the tumor behavior. Galectin-3 (Gal-3), a ß-galactoside-binding lectin, has emerged as a major effector in cancer progression, including melanoma behavior. Data from melanoma models and patient studies reveal that Gal-3 expression is dysregulated, both intracellularly and extracellularly, throughout the stages of melanoma progression. This review summarizes the most recent data and hypotheses on Gal-3 and its tumor-modulating functions, highlighting its role in driving melanoma growth, invasion, and metastatic colonization. It also provides insight into potential Gal-3-targeted strategies for melanoma diagnosis and treatment.

The Potential Role of Exosomal Proteins in Prostate Cancer

Prostate cancer is the most prevalent malignant tumor in men across developed countries. Traditional diagnostic and therapeutic methods for this tumor have become increasingly difficult to adapt to today’s medical philosophy, thus compromising early detection, diagnosis, and treatment. Prospecting for new diagnostic markers and therapeutic targets has become a hot topic in today’s research. Notably, exosomes, small vesicles characterized by a phospholipid bilayer structure released by cells that is capable of delivering different types of cargo that target specific cells to regulate biological properties, have been extensively studied. Exosomes composition, coupled with their interactions with cells make them multifaceted regulators in cancer development. Numerous studies have described the role of prostate cancer-derived exosomal proteins in diagnosis and treatment of prostate cancer. However, so far, there is no relevant literature to systematically summarize its role in tumors, which brings obstacles to the later research of related proteins. In this review, we summarize exosomal proteins derived from prostate cancer from different sources and summarize their roles in tumor development and drug resistance.

Galectin Family Members: Emerging Novel Targets for Lymphoma Therapy?

The galectin family of proteins has high affinity with β-galactoside-containing glycans. These proteins participate in cell growth and differentiation, cell adhesion, cell signal transduction, cell apoptosis, and other cellular activities. In recent years, a large number of studies have described the expression and correlation of galectins in different tumors. Each member of the family plays a vital role in tumor growth, progression, angiogenesis, adhesion, and tumor immune escape. Studies on the roles of galectins in lymphoma have mainly involved galectin-1, -3, -7, and -9. The results suggest that galectins may become novel targets for precise tumor treatment. This article reviews current research progress regarding galectins in lymphoma and provides new ideas for exploring them as novel targets for treating lymphoma and other important medical issues.

Galectin-3 in Kidney Diseases: From an Old Protein to a New Therapeutic Target

Galectin-3 (Gal-3) is a 30KDa lectin implicated in multiple pathophysiology pathways including renal damage and fibrosis. Gal-3 binds β-galactoside through its carbohydrate-recognition domain. From intra-cellular to extra-cellular localization, Gal-3 has multiple roles including transduction signal pathway, cell-to-cell adhesion, cell to extracellular matrix adhesion, and immunological chemoattractant protein. Moreover, Gal-3 has also been linked to kidney disease in both preclinical models and clinical studies. Gal-3 inhibition appears to improve renal disease in several pathological conditions, thus justifying the development of multiple drug inhibitors. This review aims to summarize the latest literature regarding Gal-3 in renal pathophysiology, from its role as a biomarker to its potential as a therapeutic agent.

CircRNA RERE Promotes the Oxidative Stress-Induced Apoptosis and Autophagy of Nucleus Pulposus Cells through the miR-299-5p/Galectin-3 Axis

Intervertebral disc degeneration (IDD) is widely accepted as a cause of low back pain and related degenerative musculoskeletal disorders. Nucleus pulposus (NP) cell loss is closely related to IDD progression. Thus, investigating the specifically targeted therapeutic agents against NP cell loss depends on understanding the molecular mechanisms. In this study, human NP cells were treated with hydrogen peroxide (H2O2). Cell viability was assessed by using the Cell Counting Kit-8 (CCK-8) kit. The expression of circRNA arginine-glutamic acid dipeptide repeats (hsa_circ_RERE) and miR-299-5p was analyzed by real-time quantitative PCR. Western blot analysis was used to assess the protein expression levels. The autophagy levels in NP cells were detected by using an electronic microscope, LC3B protein immunofluorescence, and western blot. The apoptosis levels of NP cells were detected by flow cytometry and western blot. Dual-luciferase reporter assay analyzed the miR-299-5p bound to circ_RERE and galectin-3. Our results revealed that H2O2 significantly inhibited the viability of NP cells, promoted apoptosis and autophagy, and upregulated galectin-3 expression. miR-299-5p was reduced in IDD and H2O2-induced NP cells. The overexpression of miR-299-5p promoted cell viability and attenuated apoptosis and autophagy under H2O2 treatment. Besides, circ_RERE was upregulated in IDD and H2O2-induced NP cells. However, knockdown of circ_RERE reversed the effects of miR-299-5p overexpression on cell viability, apoptosis, and autophagy in NP cells. We propose that circ_RERE promotes the H2O2-induced apoptosis and autophagy of NP cells through the miR-299-5p/galectin-3 axis and may provide a new target for the clinical treatment of IDD.

Galectin‑3 blockade suppresses the growth of cetuximab‑resistant human oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a cancer associated with high mortality (accounting for 3.1/100,000 deaths per year in Brazil in 2013) and a high frequency of amplification in the expression of the epidermal growth factor receptor (EGFR). Treatment with the EGFR inhibitor cetuximab leads to drug resistance in patients with OSCC due to unknown mechanisms. Galectin‑3 (Gal‑3) is a β‑galactoside binding lectin that regulates multiple signaling pathways in cells. The present study aimed to investigate the effect of Gal‑3 in cetuximab‑resistant (cet‑R) OSCC. The OSCC HSC3 cell line was selected to establish a mouse xenograft model, which was treated with cetuximab to induce resistance. Subsequently, a Gal‑3 inhibitor was used to treat cet‑R tumors, and the tumor volume was monitored. The expression of Gal‑3, phosphorylated (p)‑ERK1/2 and p‑Akt was assessed using immunohistochemistry. The combined effect of cetuximab and the Gal‑3 inhibitor on HSC3 tumor xenografts was also investigated. HSC3 cells were cultured in vitro to investigate the regulatory effects of Gal‑3 on ERK1/2 and Akt via western blotting. In addition, the effects of the Gal‑3 inhibitor on the proliferation, colony formation, invasion and apoptosis of HSC3 cells were investigated by performing Cell Counting Kit‑8, colony formation, Transwell and apoptosis assays, respectively. In cet‑R OSCC tumors, increased expression of Gal‑3, p‑ERK1/2 and p‑Akt was observed. Further research demonstrated that Gal‑3 regulated the expression of both ERK1/2 and Akt in HSC3 cells by promoting phosphorylation. Moreover, the Gal‑3 inhibitor decreased the proliferation and invasion, but increased the apoptosis of cet‑R HSC3 cells. In addition, the Gal‑3 inhibitor suppressed the growth of cet‑R tumors. Collectively, the results indicated that the Gal‑3 inhibitor and cetuximab displayed a synergistic inhibitory effect on OSCC tumors. In summary, the present study demonstrated that Gal‑3 may serve an important role in cet‑R OSCC. The combination of cetuximab and the Gal‑3 inhibitor may display a synergistic antitumor effect, thereby inhibiting the development of cetuximab resistance in OSCC.

Therapeutic potential of galectin-1 and galectin-3 in autoimmune diseases

Galectins are a highly conserved protein family that binds to β-galactosides. Different members of this family play a variety of biological functions in physiological and pathological processes such as angiogenesis, regulation of immune cell activity, and cell adhesion. Galectins are widely distributed and play a vital role both inside and outside cells. It can regulate homeostasis and immune function in vivo through mechanisms such as apoptosis. Recent studies indicate that galectins exhibit pleiotropic roles in inflammation. Furthermore, emerging studies have found that galectins are involved in the occurrence and development of autoimmune diseases such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), type 1 diabetes (T1D) and systemic sclerosis (SSc) by regulating cell adhesion, apoptosis, and other mechanisms. This review will briefly discuss the biological characteristics of the two most widely expressed and extensively explored members of the galectin family, galectin-1 and galectin-3, as well as their pathogenetic and therapeutic roles in autoimmune diseases. These information may provide a novel and promising therapeutic target for autoimmune diseases.

Perspectives on immune checkpoint ligands: expression, regulation, and clinical implications

In the tumor microenvironment, immune checkpoint ligands (ICLs) must be expressed in order to trigger the inhibitory signal via immune checkpoint receptors (ICRs). Although ICL expression frequently occurs in a manner intrinsic to tumor cells, extrinsic factors derived from the tumor microenvironment can fine-tune ICL expression by tumor cells or prompt non-tumor cells, including immune cells. Considering the extensive interaction between T cells and other immune cells within the tumor microenvironment, ICL expression on immune cells can be as significant as that of ICLs on tumor cells in promoting anti-tumor immune responses. Here, we introduce various regulators known to induce or suppress ICL expression in either tumor cells or immune cells, and concise mechanisms relevant to their induction. Finally, we focus on the clinical significance of understanding the mechanisms of ICLs for an optimized immunotherapy for individual cancer patients.

Galectin-3 immunolabelling correlates with BCL2 expression in canine cutaneous mast cell tumours

Mast cell tumour (MCT) is the most frequent skin neoplasm in dogs. These tumours are characterised by variable behaviour and clinical presentation that make prognosis an important and challenging task in the veterinary practice. Galectin-3 (Gal-3) is known to influence several biological processes that are important in the cancer context and has been described as a prognostic marker for several human cancers. The aim of the present work was to characterise Gal-3 immunolabelling in canine cutaneous MCTs and to investigate its value as a prognostic marker for the disease. Thirty-four random cases of canine cutaneous MCT that were surgically treated with wide margins were included in this study. Gal-3 expression was evaluated using immunohistochemistry and the results were compared with the expression of apoptosis-related proteins, Ki67 index, histopathological grades, mortality due to the disease and post-surgical survival. The majority of the MCTs (65.8%) were positive for Gal-3. Gal-3 immunolabelling was variable among the samples (2.7%-86.8% of the neoplastic cells). The protein was located in the cytoplasm or in the cytoplasm and the nucleus. Gal-3 positivity was correlated with BCL2 expression (P < 0.001; r = 0.604), but not with Ki67 and BAX. No significant differences were detected between histological grades or in the survival analysis. Gal-3 expression correlates with BCL2 expression in MCTs. Although an efficient marker for several human neoplasms, the results presented herein suggest that Gal-3 immunolabelling is not an independent prognostic indicator for this disease.

Targeted disruption of galectin 3 in mice delays the first wave of spermatogenesis and increases germ cell apoptosis

Galectin 3 is a multifunctional lectin implicated in cellular proliferation, differentiation, adhesion, and apoptosis. This lectin is broadly expressed in testicular somatic cells and germ cells, and is upregulated during testicular development. Since the role of galectin 3 in testicular function remains elusive, we aimed to characterize the role of galectin 3 in testicular physiology. We found that galectin 3 transgenic mice (Lgals3-/-) exhibited significantly decreased testicular weight in adulthood compared to controls. The transgenic mice also exhibited a delay to the first wave of spermatogenesis, a decrease in the number of germ cells at postnatal day 5 (P5) and P15, and defective Sertoli cell maturation. Mechanistically, we found that Insulin-like-3 (a Leydig cell marker) and enzymes involved in steroid biosynthesis were significantly upregulated in adult Lgals3-/- testes. These observations were accompanied by increased serum testosterone levels. To determine the underlying causes of the testicular atrophy, we monitored cellular apoptosis. Indeed, adult Lgals3-/- testicular cells exhibited an elevated apoptosis rate that is likely driven by downregulated Bcl-2 and upregulated Bax and Bak expression, molecules responsible for live/death cell balance. Moreover, the percentage of testicular macrophages within CD45+ cells was decreased in Lgals3-/- mice. These data suggest that galectin 3 regulates spermatogenesis initiation and Sertoli cell maturation in part, by preventing germ cells from undergoing apoptosis and regulating testosterone biosynthesis. Going forward, understanding the role of galectin 3 in testicular physiology will add important insights into the factors governing the development of germ cells and steroidogenesis and delineate novel biomarkers of testicular function.

Altered expression of genes related to innate antifungal immunity in the absence of galectin-3

Galectin-3 (Gal-3) is the most studied member of the animal galectin family, which comprises β-galactoside-binding lectins and participates in several cellular events. Its expression in cells involved in innate and adaptive immunity is related to anti- and proinflammatory functions, signaling an important role in inflammatory, infectious, and tumorigenesis processes. Mice deficient in Gal-3 exhibit important phenotypes, but it is unclear whether these phenotypes reflect an impairment of the functions of this protein. Gal-3 plays an important role in modulating the immune response to different pathogenic microorganisms. However, the role of Gal-3 in immunity to infection is still poorly understood. Therefore, we investigated the effects of Gal-3 deletion on the expression of genes involved in the innate immune response in the lungs, spleens, and brains of Gal-3 KO mice. Gene profiling expression analysis suggested that Gal-3 deletion resulted in differentially modulated expression of the genes encoding beta-glucan, mannose and chitin-responsive pattern recognition receptors, signal transduction, inflammation, and phagocytosis. Our data thus suggest the importance of Gal-3 expression in the host innate immune system.

Non-classical role of Galectin-3 in cancer progression: translocation to nucleus by carbohydrate-recognition independent manner

Galectin-3 is a carbohydrate-binding protein and regulates diverse functions, including cell proliferation and differentiation, mRNA splicing, apoptosis induction, immune surveillance and inflammation, cell adhesion, angiogenesis, and cancer-cell metastasis. Galectin-3 is also recommended as a diagnostic or prognostic biomarker of various diseases, including heart disease, kidney disease, and cancer. Galectin-3 exists as a cytosol, is secreted in extracellular spaces on cells, and is also detected in nuclei. It has been found that galectin-3 has different functions in cellular localization: (i) Extracellular galectin-3 mediates cell attachment and detachment. (ii) cytosolic galectin-3 regulates cell survival by blocking the intrinsic apoptotic pathway, and (iii) nuclear galectin-3 supports the ability of the transcriptional factor for target gene expression. In this review, we focused on the role of galectin-3 on translocation from cytosol to nucleus, because it happens in a way independent of carbohydrate recognition and accelerates cancer progression. We also suggested here that intracellular galecin-3 could be a potent therapeutic target in cancer therapy. [BMB Reports 2020; 53(4): 173-180].

Targeting the CRD F-face of Human Galectin-3 and Allosterically Modulating Glycan Binding by Angiostatic PTX008 and a Structurally Optimized Derivative

Calix[4]arene PTX008 is an angiostatic agent that inhibits tumor growth in mice by binding to galectin-1, a β-galactoside-binding lectin. To assess the affinity profile of PTX008 for galectins, we used ¹⁵ N,¹ H HSQC NMR spectroscopy to show that PTX008 also binds to galectin-3 (Gal-3), albeit more weakly. We identified the contact site for PTX008 on the F-face of the Gal-3 carbohydrate recognition domain. STD NMR revealed that the hydrophobic phenyl ring crown of the calixarene is the binding epitope. With this information, we performed molecular modeling of the complex to assist in improving the rather low affinity of PTX008 for Gal-3. By removing the N-dimethyl alkyl chain amide groups, we produced PTX013 whose reduced alkyl chain length and polar character led to an approximately eightfold stronger binding than PTX008. PTX013 also binds Gal-1 more strongly than PTX008, whereas neither interacts strongly, if at all, with Gal-7. In addition, PTX013, like PTX008, is an allosteric inhibitor of galectin binding to the canonical ligand lactose. This study broadens the scope for galectin targeting by calixarene-based compounds and opens the perspective for selective galectin blocking.

Overexpression of Galectin-1 and Galectin-3 in hepatocellular carcinoma

Galectins (Gals) are evolutionarily conserved proteins that bind to β-galactoside containing glycans. Abnormal expression of Gals is associated with the development, progression, and metastasis of different types of cancer. Among the 11 Gals identified in humans, the roles of Gal-1 and Gal-3 have been extensively investigated in various tumors. Here, we summarize the roles of overly expressed Gal-1 and Gal-3 in the pathogenesis of hepatocellular carcinoma (HCC). The overexpression of Gal-1 and Gal-3 correlates with tumor growth, HCC cell migration and invasion, tumor aggressiveness, metastasis, and poor prognosis. A potentially promising future treatment strategy for HCC may include the combination of immunotherapy with Gal-1 inhibition. Additional research is warranted to investigate targeting Gal-1 and Gal-3 for HCC treatment.

Tumor resistance mechanisms and their consequences on γδ T cell activation

Human γδ T lymphocytes are predominated by two major subsets, defined by the variable domain of the δ chain. Both, Vδ1 and Vδ2 T cells infiltrate in tumors and have been implicated in cancer immunosurveillance. Since the localization and distribution of tumor-infiltrating γδ T cell subsets and their impact on survival of cancer patients are not completely defined, this review summarizes the current knowledge about this issue. Different intrinsic tumor resistance mechanisms and immunosuppressive molecules of immune cells in the tumor microenvironment have been reported to negatively influence functional properties of γδ T cell subsets. Here, we focus on selected tumor resistance mechanisms including overexpression of cyclooxygenase (COX)-2 and indolamine-2,3-dioxygenase (IDO)-1/2, regulation by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)/TRAIL-R4 pathway and the release of galectins. These inhibitory mechanisms play important roles in the cross-talk of γδ T cell subsets and tumor cells, thereby influencing cytotoxicity or proliferation of γδ T cells and limiting a successful γδ T cell-based immunotherapy. Possible future directions of a combined therapy of adoptively transferred γδ T cells together with γδ-targeting bispecific T cell engagers and COX-2 or IDO-1/2 inhibitors or targeting sialoglycan-Siglec pathways will be discussed and considered as attractive therapeutic options to overcome the immunosuppressive tumor microenvironment.

Galectin-3 not Galectin-9 as a candidate prognosis marker for hepatocellular carcinoma

Background

Galectins (Gal) are a family of protein that bind to the β-galactoside of glycoproteins. It modulates a variety of biological functions, such as tumor growth, angiogenesis and tumor metastasis. A series of experimental and clinical evidences have been reported to support a correlation between galectin expressions and neoplastic transformation, progression and prognosis. The objective of this study was to estimate the expression of Gal-3 and Gal-9 in order to evaluate their relation to hepatocellular carcinoma (HCC) -related clinical features and their prognostic values.

Methods

We evaluated Gal-3 and Gal-9 expression in 247 HCC patients by a tissue microarray immunohistochemistry method, then analyzed the relationship between expression levels of Gal-3 and Gal-9 protein and tumor parameters or clinical outcomes.

Results

The Gal-3 expression was significantly higher in tumor tissues compared with adjacent non-tumor tissues (P < 0.001), while no significant differences of Gal-9 was detected (P = 0.222). A higher Gal-3 expression was significantly associated with lymph-vascular invasion (P = 0.049), poor histological differentiation (P = 0.016), and no cirrhosis (P = 0.040). In contrast, a lower Gal-9 expression was related to lymph-vascular invasion (P = 0.012) and poor histological differentiation (P = 0.002). Survival analysis showed that patients with higher Gal-3 expression had worse overall survival (P = 0.012) , however no correlation was found between Gal-9 expression and survival (P = 0.185). Multivariate analysis showed that multiple tumor (HR = 1.94, 95% CI [1.36–2.78]), tumor size ≥ 5 cm (HR = 1.51, 95% CI [1.07–2.12]), Lymph-vascular invasion (HR = 1.45, 95% CI [1.00–2.10]) and Gal-3 expression (HR = 1.57, 95% CI [1.06–2.33]) were independent influencing factors of prognosis in patients with hepatocellular carcinoma.

Conclusion

Gal-3 was expected to serve as a novel prognostic marker of hepatocellular carcinoma, while Gal-9 expression was only related to tumor progression.

Could Galectin 3 Be a Good Prognostic Factor in Endometrial Cancer?

Galectin 3 is a modulator of several basic biological functions. It may be involved in the development of obesity and type 2 diabetes—risk factors of endometrial cancer. The study involved 144 patients, after abrasion due to postmenopausal bleeding. Galectin 3 concentrations were quantified in serum by multiplex fluorescent bead-based immunoassays. Median serum galectin 3 concentrations revealed significant differences between FIGO III and IV vs. FIGO I and II patients. Statistically higher concentrations were reported for patients with lymph node metastases compared to patients without it (p = 0.001) as well as in patients with lymphovascular space invasion compared to patients without LVSI (p = 0.02). No statistically significant differences were observed for median of galectin 3 levels depending on the surgical procedure (laparoscopy vs. laparotomy, p = 0.0608). Patients with galectin 3 levels exceeding the median value were characterized by overall survival being shorter by 11.9 months. High levels of galectin 3 were correlated with shorter disease-free survival, the difference is up to 14.8 months. Galectin 3 can be an independent prognostic factor in patients with endometrial cancer. Among the recognized prognostic factors and the concentrations of the galectin 3 marker at the adopted time points, the univariate analysis showed a significant effect of staging, grading, and cutoff galectin 3 on the OS. For multivariate analysis, the galectin 3 cutoff point had the greatest significant impact on OS.

CD146, from a melanoma cell adhesion molecule to a signaling receptor

CD146 was originally identified as a melanoma cell adhesion molecule (MCAM) and highly expressed in many tumors and endothelial cells. However, the evidence that CD146 acts as an adhesion molecule to mediate a homophilic adhesion through the direct interactions between CD146 and itself is still lacking. Recent evidence revealed that CD146 is not merely an adhesion molecule, but also a cellular surface receptor of miscellaneous ligands, including some growth factors and extracellular matrixes. Through the bidirectional interactions with its ligands, CD146 is actively involved in numerous physiological and pathological processes of cells. Overexpression of CD146 can be observed in most of malignancies and is implicated in nearly every step of the development and progression of cancers, especially vascular and lymphatic metastasis. Thus, immunotherapy against CD146 would provide a promising strategy to inhibit metastasis, which accounts for the majority of cancer-associated deaths. Therefore, to deepen the understanding of CD146, we review the reports describing the newly identified ligands of CD146 and discuss the implications of these findings in establishing novel strategies for cancer therapy.

Cell Type- and Stimulation-Dependent Transcriptional Programs Regulated by Atg16L1 and Its Crohn's Disease Risk Variant T300A

Genome-wide association studies have identified common genetic variants impacting human diseases; however, there are indications that the functional consequences of genetic polymorphisms can be distinct depending on cell type-specific contexts, which produce divergent phenotypic outcomes. Thus, the functional impact of genetic variation and the underlying mechanisms of disease risk are modified by cell type-specific effects of genotype on pathological phenotypes. In this study, we extend these concepts to interrogate the interdependence of cell type- and stimulation-specific programs influenced by the core autophagy gene Atg16L1 and its T300A coding polymorphism identified by genome-wide association studies as linked with increased risk of Crohn's disease. We applied a stimulation-based perturbational profiling approach to define Atg16L1 T300A phenotypes in dendritic cells and T lymphocytes. Accordingly, we identified stimulus-specific transcriptional signatures revealing T300A-dependent functional phenotypes that mechanistically link inflammatory cytokines, IFN response genes, steroid biosynthesis, and lipid metabolism in dendritic cells and iron homeostasis and lysosomal biogenesis in T lymphocytes. Collectively, these studies highlight the combined effects of Atg16L1 genetic variation and stimulatory context on immune function.

A Chimeric Signal Peptide-Galectin-3 Conjugate Induces Glycosylation-Dependent Cancer Cell-Specific Apoptosis

PURPOSE

Exploitation of altered glycosylation in cancer is a major goal for the design of new cancer therapy. Here, we designed a novel secreted chimeric signal peptide-Galectin-3 conjugate (sGal-3) and investigated its ability to induce cancer-specific cell death by targeting aberrantly N-glycosylated cell surface receptors on cancer cells.

EXPERIMENTAL DESIGN

sGal-3 was genetically engineered from Gal-3 by extending its N-terminus with a noncleavable signal peptide from tissue plasminogen activator. sGal-3 killing ability was tested on normal and tumor cells in vitro and its antitumor activity was evaluated in subcutaneous lung cancer and orthotopic malignant glioma models. The mechanism of killing was investigated through assays detecting sGal-3 interaction with specific glycans on the surface of tumor cells and the elicited downstream proapoptotic signaling.

RESULTS

We found sGal-3 preferentially binds to β1 integrin on the surface of tumor cells due to aberrant N-glycosylation resulting from cancer-associated upregulation of several glycosyltransferases. This interaction induces potent cancer-specific death by triggering an oncoglycan-β1/calpain/caspase-9 proapoptotic signaling cascade. sGal-3 could reduce the growth of subcutaneous lung cancers and malignant gliomas in brain, leading to increased animal survival.

CONCLUSIONS

We demonstrate that sGal-3 kills aberrantly glycosylated tumor cells and antagonizes tumor growth through a novel integrin β1-dependent cell-extrinsic apoptotic pathway. These findings provide proof-of-principle that aberrant N-oncoglycans represent valid cancer targets and support further translation of the chimeric sGal-3 peptide conjugate for cancer therapy.

Cancer immunotherapy needs to learn how to stick to its guns

Cancer immunotherapy and its budding effectiveness at improving patient outcomes has revitalized our hope to fight cancer in a logical and safe manner. Immunotherapeutic approaches to reengage the immune system have largely focused on reversing immune checkpoint inhibitor pathways, which suppress the antitumor response. Although these approaches have generated much excitement, they still lack absolute success. Interestingly, newly described host-tumor sugar chains (glycosylations) and glycosylation-binding proteins (lectins) play key roles in evading the immune system to determine cancer progression. In this issue of the JCI, Nambiar et al. used patient head and neck tumors and a mouse model system to investigate the role of galactose-binding lectin 1 (Gal1) in immunotherapy resistance. The authors demonstrated that Gal1 can affect immune checkpoint inhibitor therapy by increasing immune checkpoint molecules and immunosuppressive signaling in the tumor. Notably, these results suggest that targeting a tumor's glycobiological state will improve treatment efficacy.

Galectin 3 Deficiency Alters Chondrocyte Primary Cilium Formation and Exacerbates Cartilage Destruction via Mitochondrial Apoptosis

Mechanical overload and aging are the main risk factors of osteoarthritis (OA). Galectin 3 (GAL3) is important in the formation of primary cilia, organelles that are able to sense mechanical stress. The objectives were to evaluate the role of GAL3 in chondrocyte primary cilium formation and in OA in mice. Chondrocyte primary cilium was detected in vitro by confocal microscopy. OA was induced by aging and partial meniscectomy of wild-type (WT) and Gal3-null 129SvEV mice (Gal3^−/−). Primary chondrocytes were isolated from joints of new-born mice. Chondrocyte apoptosis was assessed by Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), caspase 3 activity and cytochrome c release. Gene expression was assessed by qRT-PCR. GAL3 was localized at the basal body of the chondrocyte primary cilium. Primary cilia of Gal3^−/− chondrocytes were frequently abnormal and misshapen. Deletion of Gal3 triggered premature OA during aging and exacerbated joint instability-induced OA. In both aging and surgery-induced OA cartilage, levels of chondrocyte catabolism and hypertrophy markers and apoptosis were more severe in Gal3^−/− than WT samples. In vitro, Gal3 knockout favored chondrocyte apoptosis via the mitochondrial pathway. GAL3 is a key regulator of cartilage homeostasis and chondrocyte primary cilium formation in mice. Gal3 deletion promotes OA development.

Cell membrane-coated gold nanoparticles for apoptosis imaging in living cells based on fluorescent determination

A nanoprobe was developed to achieve apoptosis detection by cell membrane-functionalized gold nanoparticles (AuNP-pep@Mem). The fluorescence of the fluorescein isothiocyanate isomer I (FITC)-labeled caspase-3 substrates was quenched by the attachment to AuNPs. The fluorescence signal was recovered via the cleavage of caspase-3 under apoptotic conditions. It exhibited a low detection limit of 1.3 pg·mL^-1 with a linear range from 3.2 to 100 pg·mL^-1 for caspase-3 detection with excitation wavelength of 490 nm. After wrapped by the cell membrane, the nanoprobe was effectively delivered into cells with high cell permeability. AuNP-pep@Mem nanoprobe provided signal enhancement of 1.8 times in living cells compared to non-membrane-coated nanoparticles (AuNP-pep). In combination with its excellent stability, low LOD and good specificity, the AuNP-pep@Mem probe can be an ideal probe for fluorescence imaging of apoptosis. Graphical abstractSchematic representation of fluorescent determination for apoptosis in living cells based on cell membrane-coated gold nanoparticls.

Galectin-3 mediates pulmonary vascular endothelial cell dynamics via TRPC1/4 under acute hypoxia

Galectin-3 (Gal-3) has been implicated in various biological functions, yet little is known about its role in regulating the dynamics of pulmonary vascular endothelial cells. Gal-3 was shown to be increased in hypoxic model rats by sequencing analysis. We exposed pulmonary vessel endothelial cells (PVECs) to hypoxia or Gal-3 stimulation, following which cell apoptosis and autophagy were measured with the relevant methods. The results demonstrated that hypoxia elevated nuclear factor-κB (NF-κB) activity and Gal-3 expression. Gla-3 decreased the expression of Bcl-2, Alix, Beclin-1, Atg5, and LC3A/B. The messenger RNA and protein levels of transient receptor potential channel 1/4 (TRPC1/4) and calpain were reduced after Gal-3 treatment. Gal-3 also activated protein kinase B/glycogen synthase kinase-3 β/mammalian target of rapamycin signaling pathways in PVECs. These results suggest that a hypoxia-mediated increase in Gal-3 promotes apoptosis and inhibits autophagy by inhibiting the TRPC1/4 pathway and activating the protein kinase B/glycogen synthase kinase-3 β/mammalian target of rapamycin signaling pathway in PVECs. Furthermore, these results may provide us with a new direction to explore the pathogenesis of pulmonary artery hypertension.

NMR-based insight into galectin-3 binding to endothelial cell adhesion molecule CD146: Evidence for noncanonical interactions with the lectin's CRD β-sandwich F-face

Galectin-3 (Gal-3) binds to cell adhesion glycoprotein CD146 to promote cytokine secretion and mediate endothelial cell migration. Here, we used Nuclear Magnetic Resonance (NMR) 15N-Heteronuclear Single Quantum Coherence (HSQC) spectroscopy to investigate binding between 15N-labeled Gal-3 and the extracellular domain (eFL) of purified CD146 (five Ig-like ectodomains D1-D5) and a shorter, D5-deleted version of CD146 (D1-D4). Binding of Gal-3 and its carbohydrate recognition domain (CRD) to CD146 D1-D4 is greatly reduced vis-à-vis CD146 eFL, supporting the proposal of a larger number of glycosylation sites on D5. Even though the canonical sugar-binding β-sheet S-face (β-strands 1, 10, 3, 4, 5, 6) of the Gal-3 β-sandwich is involved in interactions with CD146 (e.g. N-linked glycosylation sites), equivalent HSQC spectral perturbations at residues on the opposing Gal-3 F-face β-sheet (β-strands 11, 2, 7, 8, 9) indicate involvement of the Gal-3 F-face in binding CD146. This is supported by the observation that addition of lactose, while significantly attenuating Gal-3 binding (primarily with the S-face) to CD146 eFL, does not abolish it. Bio-Layer Interferometry studies with Gal-3 F-face mutants yield KD values to demonstrate a significant decrease (L203A) or increase (V204A, L218A, T243A) in net binding to CD146 eFL compared to wild type Gal-3. However, HSQC lactose titrations show no highly significant effects on sugar binding to the Gal-3 CRD S-face. Overall, our findings indicate that Gal-3 binding to CD146 is more involved than simple interactions with β-galactoside epitopes on the cell receptor, and that there is a direct role for the lectin's CRD F-face in the CD146 binding process.

Synthesis of tricyclic carbohydrate–benzene hybrids as selective inhibitors of galectin-1 and galectin-8 N-terminal domains

As the galactoside binding family of galectin proteins is involved in many physiological and pathological processes, the inhibitors of these proteins are considered to be of significant interest in the treatment of diseases such as cancer and fibrosis. Herein, fused tricyclic carbohydrate–benzene hybrid core structures are reported to be the selective inhibitors of galectin-1 and the N-terminal domain of galectin-8 by a competitive fluorescence polarization assay. The key intermediates mono- or diiodo tricyclic carbohydrate–benzene hybrids were synthesized from protected 2-bromo-3-O-propargyl-d-galactose via a domino reaction and subsequently utilized for further derivatization by Stille couplings to achieve derivatives carrying substituents at C10 and/or C11. Several compounds showed affinity for the galectin-1 and galectin-8 N-terminal (8N) domains; however, weak or even no binding was observed for galectin-3. Monosubstituted derivatives at C10 or C11 exhibited better affinity for galectin-8N than di-substituted derivatives at C10 or C11. Especially, a benzyl substituent or p-fluorobenzyl substituent at C11 displayed affinity and selectivity for galectin-1 and galectin-8N over galectin-3. This suggests that tricyclic carbohydrate–benzene hybrids are promising scaffolds for the development of selective galectin-1 and galectin-8N inhibitors.

Fused tricyclic carbohydrate–benzene hybrids carrying substituents at C10 and/or C11 were designed, synthesized and evaluated as inhibitors for galectin-1 and the N-terminal domain of galectin-8.

Galectin-3 Regulates the Expression of Tumor Glycosaminoglycans and Increases the Metastatic Potential of Breast Cancer

Galectin-3 (Gal-3) is a multifunctional β-galactoside-binding lectin that once synthesized is expressed in the nucleus, cytoplasm, cell surface, and extracellular environment. Gal-3 plays an important role in breast cancer tumors due to its ability to promote interactions between cell-cell and cell-extracellular matrix (ECM) elements, increasing tumor survival and metastatic dissemination. Still, the mechanism by which Gal-3 interferes with tumor cell migration and metastasis formation is complex and not fully understood. Here, we showed that Gal-3 knockdown increased the migration ability of 4T1 murine breast cancer cells in vitro. Using the 4T1 orthotopic breast cancer spontaneous metastasis mouse model, we demonstrated that 4T1-derived tumors were significantly larger in the presence of Gal-3 (scramble) in comparison with Gal-3 knockdown 4T1-derived tumors. Nevertheless, Gal-3 knockdown 4T1 cells were outnumbered in the bone marrow in comparison with scramble 4T1 cells. Finally, we reported here a decrease in the content of cell-surface syndecan-1 and an increase in the levels of chondroitin sulfate proteoglycans such as versican in Gal-3 knockdown 4T1 cells both in vitro and in vivo. Overall, our findings establish that Gal-3 downregulation during breast cancer progression regulates cell-associated and tumor microenvironment glycosaminoglycans (GAGs)/proteoglycans (PG), thus enhancing the metastatic potential of tumor cells.

FOXD1 and Gal-3 Form a Positive Regulatory Loop to Regulate Lung Cancer Aggressiveness

Dysregulation of forkhead box D1 (FOXD1) is known to promote tumor progression; however, its molecular mechanism of action is unclear. Based on microarray analysis, we identified galectin-3/LGALS3 (Gal-3) as a potential downstream target of FOXD1, as FOXD1 transactivated Gal-3 by interacting with the Gal-3 promoter to upregulate Gal-3 in FOXD1-overexpressing CL1-0 lung cancer cells. Ectopic expression of FOXD1 increased the expression of Gal-3 and the growth and motility of lung cancer cells, whereas depletion of Gal-3 attenuated FOXD1-mediated tumorigenesis. ERK1/2 interacted with FOXD1 in the cytosol and translocated FOXD1 into the nucleus to activate Gal-3. Gal-3 in turn upregulated FOXD1 via the transcription factor proto-oncogene 1 (ETS-1) to transactivate FOXD1. The increase in ETS-1/FOXD1 expression by Gal-3 was through Gal-3-mediated integrin-β1 (ITGβ1) signaling. The overexpression of both FOXD1 and Gal-3 form a positive regulatory loop to promote lung cancer aggressiveness. Moreover, both FOXD1 and Gal-3 were positively correlated in human lung cancer tissues. Our findings demonstrated that FOXD1 and Gal-3 form a positive feedback loop in lung cancer, and interference of this loop may serve as an effective therapeutic target for the treatment of lung cancers, particularly those related to dysregulation of Gal-3.

Galectin-3 Expression Correlates with Post-surgical Survival in Canine Oral Melanomas

Malignant melanomas (MMs) represent 7% of all malignant neoplasms in dogs. Oral melanocytic neoplasms are often malignant and associated with poor prognosis. There are no universally accepted prognostic markers for canine oral melanoma. Galectin (Gal)-3 is a prognostic marker for human neoplasms such as thyroid, gastric, colorectal and prostate cancers. The protein is related to processes that favour cancer progression, such as angiogenesis, proliferation and apoptosis. The aim of the present study was to characterize the immunohistochemical expression of Gal-3 in canine oral melanomas and to compare it with post-surgical survival, the expression of apoptosis-related proteins and other known prognostic tools. Twenty-seven samples of canine oral melanomas were evaluated for Gal-3, B-cell lymphoma (BCL) 2, caspase (CASP) 3 and Ki67 expression, mitotic index and degree of nuclear atypia. Gal-3 cytoplasmic positivity was correlated positively, while nuclear positivity was correlated negatively, with survival. The intensity of BCL2 labelling was also correlated positively with Gal-3 cytoplasmic positivity. Higher nuclear atypia was observed in dogs with melanoma that died due to the tumour, as well as in dogs that survived for <1 year after surgery. We have confirmed the importance of nuclear atypia for MMs and suggest that Gal-3 is a valuable prognostic indicator for this neoplasm. More in-depth studies are needed to unveil Gal-3 functions in canine MMs using larger sample sizes.

Pleiotropic Effects of Modified Citrus Pectin

Modified citrus pectin (MCP) has a low-molecular-weight degree of esterification to allow absorption from the small intestinal epithelium into the circulation. MCP produces pleiotropic effects, including but not limited to its antagonism of galectin-3, which have shown benefit in preclinical and clinical models. Regarding cancer, MCP modulates several rate-limiting steps of the metastatic cascade. MCP can also affect cancer cell resistance to chemotherapy. Regarding fibrotic diseases, MCP modulates many of the steps involved in the pathogenesis of aortic stenosis. MCP also reduces fibrosis to the kidney, liver, and adipose tissue. Other benefits of MCP include detoxification and improved immune function. This review summarizes the pleiotropic effects of MCP.

Enzyme-Catalyzed Production of Potato Galactan-Oligosaccharides and Its Optimization by Response Surface Methodology

This work shows an optimized enzymatic hydrolysis of high molecular weight potato galactan yielding pectic galactan-oligosaccharides (PGOs), where endo-β-1,4-galactanase (galactanase) from Cellvibrio japonicus and Clostridium thermocellum was used. For this, response surface methodology (RSM) by central composite design (CCD) was applied. The parameters varied were temperature (°C), pH, incubation time (min), and enzyme/substrate ratio (U/mg). The optimized conditions for the production of low degree of polymerization (DP) PGOs were obtained for each enzyme by spectrophotometric assay and confirmed by chromatography. The optimal conditions predicted for the use of C. japonicus galactanase to obtain PGOs of DP = 2 were T = 51.8 °C, pH 5, E/S = 0.508 U/mg, and t = 77.5 min. For DP = 3, they were T = 21 °C, pH 9, E/S = 0.484 U/mg, and t = 12.5 min; and for DP = 4, they were T = 21 °C, pH 5, E/S = 0.462 U/mg, and t = 12.5 min. The efficiency results were 51.3% for substrate hydrolysis. C. thermocellum galactanase had a lower yield (35.7%) and optimized conditions predicted for PGOs of DP = 2 were T = 60 °C, pH 5, E/S = 0.525 U/mg, and time = 148 min; DP = 3 were T = 59.7 °C, pH 5, E/S = 0.506 U/mg, and time = 12.5 min; and DP = 4, were T = 34.5 °C, pH 11, E/S = 0.525 U/mg, and time = 222.5 min. Fourier transformed infrared (FT-IR) and nuclear magnetic resonance (NMR) characterizations of PGOs are presented.

Neuroinflammation induced by the peptide amyloid-β (25-35) increase the presence of galectin-3 in astrocytes and microglia and impairs spatial memory

Galectins are animal lectins that bind to β-galactosides, such as lactose and N-acetyllactosamine, contained in glycoproteins or glycolipids. Galectin-1 (Gal-1) and Galectin-3 (Gal-3) are involved in pathologies associated with the inflammatory process, cell proliferation, adhesion, migration, and apoptosis. Recent evidence has shown that the administration of Amyloid-β 25-35 (Aβ_25-35) into the hippocampus of rats increases the inflammatory response that is associated with memory impairment and neurodegeneration. Galectins could participate in the modulation of the neuroinflammation induced by the Aβ_25-35. The aim of this study was to evaluate the presence of Gal-1 and Gal-3 in the neuroinflammation induced by administration of Aβ_25-35 into the hippocampus and to examine spatial memory in the Morris water maze. After the administration of Aβ_25-35, animals were tested for learning and spatial memory in the Morris water maze. Behavioral performance showed that Aβ_25-35 didn't affect spatial learning but did impair memory, with animals taking longer to find the platform. On the day 32, hippocampus was examined for astrocytes (GFAP), microglia (Iba1), Gal-1 and Gal-3 via immunohistochemical analysis, and the cytokines IL-1β, TNF-α, IFN-γ by ELISA. This study's results showed a significant increase in the expression of Gal-3 in the microglia and astrocytes, while Gal-1 didn't increase in the dorsal hippocampus. The expression of galectins is associated with increased cytokines in the hippocampal formation of Aβ_25-35 treated rats. These findings suggest that Gal-3 could participate in the inflammation induced by administration of Aβ_25-35 and could be involved in the neurodegeneration progress and memory impairment.

Galectin-3 binds selectively to the terminal, non-reducing end of β(1→4)-galactans, with overall affinity increasing with chain length

Galactans are linear polysaccharides of β(1→4)-linked galactose residues. Although they can antagonize galectin function, the nature of their binding to galectins needs to be better defined to develop them as drugs. Here, we investigated interactions between galectin-3 (Gal-3) and a series of galactans ranging in weight average molecular weight from 670 to 7550 Da. 15N-1H HSQC NMR studies with 15N-labeled Gal-3 carbohydrate recognition domain (CRD) indicate that each of these galactans interacts primarily with residues in β-strands 4, 5 and 6 on the canonical, β-galactoside sugar binding S-face. Although these galactans also bind to full length Gal-3 (CRD plus N-terminal tail) to the same extent, it appears that binding to the S-face attenuates interactions between the CRD F-face and N-terminal tail, making interpretation of site-specific binding unclear. Following assignment of galactan 13C and 1H resonances using HSQC, HMBC and TOCSY experiments, we used 13C-1H HSQC data to demonstrate that the Gal-3 CRD binds to the terminal, non-reducing end of these galactans, regardless of their size, but with binding affinity increasing as the galactan chain length increases. Overall, our findings increase understanding as to how galactans interact with Gal-3 at the non-reducing, terminal end of galactose-containing polysaccharides as found on the cell surface.

Decoding the sweet regulation of apoptosis: the role of glycosylation and galectins in apoptotic signaling pathways

Glycosylation and glycan-binding proteins such as galectins play an important role in the control of cell death signaling. Strikingly, very little attention has been given so far to the understanding of the molecular details behind this key regulatory network. Glycans attached to the death receptors such as CD95 and TRAIL-Rs, either alone or in a complex with galectins, might promote or inhibit apoptotic signals. However, we have just started to decode the functions of galectins in the modulation of extrinsic and intrinsic apoptosis. In this work, we have discussed the current understanding of the glycosylation-galectin regulatory network in CD95- as well as TRAIL-R-induced apoptosis and therapeutic strategies based on targeting galectins in cancer.

Increased serum levels of Galectin-9 in patients with chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is the most common type of leukemia in adults. Despite improvements in treatment, CLL is still considered an incurable disease. The aim of the present study was to evaluate galectin-1, -3 and -9 (Gal-1, -3 and -9) and Gal-3 binding protein (Gal-3BP) as prognostic and predictive factors in patients with CLL. Serum concentrations of Gal-1, -3 and -9 and Gal-3BP were measured in 48 patients with CLL and 30 control patients, using multiplex bead arrays. In patients with CLL, galectin concentrations were assessed prior to, during and following treatment. In patients with CLL who were untreated, galectin concentrations were measured twice with a 6-month interval. The serum level of Gal-9 was significantly increased (P<0.0001) in patients with CLL compared with the control group, and was associated with the clinical stage according to Binet classification, as well as poor cytogenetic and serum CLL prognostic factors. In addition, patients with CLL, who exhibited treatment failure, exhibited higher concentrations of Gal-9 (P=0.06) and Gal-3BP (P=0.009) at the end of the treatment when compared with patients under complete remission or stabilization of the disease. The serum level of Gal-3 was significantly decreased (P=0.012) in patients with CLL compared with the control group. These results suggest that Gal-9 is a potential prognostic factor in patients with CLL. The predictive value of Gal-9 requires further study in larger cohorts of patients.