Galectin-3 expression is induced in cirrhotic liver and hepatocellular carcinoma

Glycolipids and Lectins in Endocytic Uptake Processes

A host of endocytic processes has been described at the plasma membrane of eukaryotic cells. Their categorization has most commonly referenced cytosolic machinery, of which the clathrin coat has occupied a preponderant position. In what concerns intra-membrane constituents, the focus of interest has been on phosphatidylinositol lipids and their capacity to orchestrate endocytic events on the cytosolic leaflet of the membrane. The contribution of extracellular determinants to the construction of endocytic pits has received much less attention, depite the fact that (glyco)sphingolipids are exoplasmic leaflet fabric of membrane domains, termed rafts, whose contributions to predominantly clathrin-independent internalization processes is well recognized. Furthermore, sugar modifications on extracellular domains of proteins, and sugar-binding proteins, termed lectins, have also been linked to the uptake of endocytic cargoes at the plasma membrane. In this review, we first summarize these contributions by extracellular determinants to the endocytic process. We thus propose a molecular hypothesis - termed the GL-Lect hypothesis - on how GlycoLipids and Lectins drive the formation of compositional nanoenvrionments from which the endocytic uptake of glycosylated cargo proteins is operated via clathrin-independent carriers. Finally, we position this hypothesis within the global context of endocytic pathway proposals that have emerged in recent years.

Molecular regulation of galectin-3 expression and therapeutic implication in cancer progression

Galectin-3, a multifunctional protein, distributes inside and outside cells and plays an important role in tumor cell adhesion, proliferation, differentiation, angiogenesis, and metastasis in multiple tumors. Changes in galectin-3 expression are commonly seen in cancer and pre-cancerous conditions. Therefore, to understand the molecular regulation of galectin-3 expression could aid the development of new approach for cancer treatment. This review summarizes different expression of galectin-3 in cancer cells and patients' serum, the regulation mechanism and the potential therapeutic targets of galectin-3 in cancer progression.

Galectin-1 Controls the Proliferation and Migration of Liver Sinusoidal Endothelial Cells and Their Interaction With Hepatocarcinoma Cells

Galectin-1 (Gal1), a β-galactoside-binding protein elevated in hepatocellular carcinoma (HCC), promotes epithelial-mesenchymal transition (EMT) and its expression correlates with HCC growth, invasiveness, and metastasis. During the early stages of HCC, transforming growth factor β1 (TGF-β1 ) acts as a tumor suppressor; however in advanced stages, HCC cells lose their cytostatic response to TGF-β1 and undergo EMT. Here, we investigated the role of Gal1 on liver endothelial cell biology, and the interplay between Gal1 and TGF-β1 in HCC progression. By Western blot and immunofluorescence, we analyzed Gal1 expression, secretion and localization in HepG2 and HuH-7 human HCC cells, and in SK-HEP-1 human liver sinusoidal endothelial cells (SECs). We used loss-of-function and gain-of-function experiments to down- or up-regulate Gal1 expression, respectively, in HepG2 cells. We cultured SK-HEP-1 cells with conditioned media from HCC cells secreting different levels of Gal1, and demonstrated that Gal1 derived from tumor hepatocytes induced its own expression in SECs. Colorimetric and scratch-wound assays revealed that secretion of Gal1 by HCC cells induced SEC proliferation and migration. Moreover, by fluorescence microscopy we demonstrated that Gal1 promoted glycan-dependent heterotypic adhesion of HepG2 cells to SK-HEP-1 SECs. Furthermore, TGF-β1 induced Gal1 expression and secretion by HCC cells, and promoted HepG2 cell adhesion to SK-HEP-1 SECs through a Gal1-dependent mechanism. Finally, Gal1 modulated HepG2 cell proliferation and sensitivity to TGF-β1 -induced growth inhibition. Our results suggest that Gal1 and TGF-β1 might function coordinately within the HCC microenvironment to regulate tumor growth, invasion, metastasis, and angiogenesis.

Galectin-3 as a Potential Target to Prevent Cancer Metastasis

Interactions between two cells or between cell and extracellular matrix mediated by protein–carbohydrate interactions play pivotal roles in modulating various biological processes such as growth regulation, immune function, cancer metastasis, and apoptosis. Galectin-3, a member of the β-galactoside-binding lectin family, is involved in fibrosis as well as cancer progression and metastasis, but the detailed mechanisms of its functions remain elusive. This review discusses its structure, carbohydrate-binding properties, and involvement in various aspects of tumorigenesis and some potential carbohydrate ligands that are currently investigated to block galectin-3 activity.

Galectin 3 regulates HCC cell invasion by RhoA and MLCK activation

Hepatocellular carcinoma (HCC) carries a poor prognosis with no effective treatment available other than liver transplantation for selected patients. Vascular invasion of HCC is one of the most important negative predictor of survival. As the regulation of invasion of HCC cells is not well understood, our aim was to study the mechanisms by which galectin 3, a β-galactosidase-binding lectin mediates HCC cell migration. HCC was induced by N-diethylnitrosamine in wild-type and galectin 3(-/-) mice, and tumor formation, histology, and tumor cell invasion were assessed. The galectin 3(-/-) mice developed significantly smaller tumor burden with a less invasive phenotype than the wild-type animals. Galectin 3 was upregulated in the wild-type HCC tumor tissue, but not in the surrounding parenchyma. Galectin 3 expression in HCC was induced by NF-κB transactivation as determined by chromatin immunoprecipitation assays. In vitro studies assessed the pro-migratory effects of galectin 3. The migration of hepatoma cells was significantly decreased after transfection by the galectin 3 siRNA and also after using the Rho kinase inhibitor Y-27632. The reorganization of the actin cytoskeleton, RhoA GTPase activity and the phosphorylation of MLC2 (myosin light chain 2) were decreased in the galectin 3 siRNA-transfected cells. In addition, in vitro and in vivo evidence showed that galectin 3 deficiency reduced hepatoma cell proliferation and increased their apoptosis rate. In conclusion, galectin 3 is an important lectin that is induced in HCC cells, and promotes hepatoma cell motility and invasion by an autocrine pathway. Targeting galectin 3 therefore could be an important novel treatment strategy to halt disease progression.

Galectin-3 Ablation Enhances Liver Steatosis, but Attenuates Inflammation and IL-33-Dependent Fibrosis in Obesogenic Mouse Model of Nonalcoholic Steatohepatitis

The importance of Galectin-3 (Gal-3) in obesity-associated liver pathology is incompletely defined. To dissect the role of Gal-3 in fibrotic nonalcoholic steatohepatitis (NASH), Gal-3-deficient (LGALS3(-/-)) and wild-type (LGALS3(+/+)) C57Bl/6 mice were placed on an obesogenic high fat diet (HFD, 60% kcal fat) or standard chow diet for 12 and 24 wks. Compared to WT mice, HFD-fed LGALS3(-/-) mice developed, in addition to increased visceral adiposity and diabetes, marked liver steatosis, which was accompanied with higher expression of hepatic PPAR-γ, Cd36, Abca-1 and FAS. However, as opposed to LGALS3(-/-) mice, hepatocellular damage, inflammation and fibrosis were more extensive in WT mice which had an elevated number of mature myeloid dendritic cells, proinflammatory CD11b(+)Ly6C(hi) monocytes/macrophages in liver, peripheral blood and bone marrow, and increased hepatic CCL2, F4/80, CD11c, TLR4, CD14, NLRP3 inflammasome, IL-1β and NADPH-oxidase enzymes mRNA expression. Thus, obesity-driven greater steatosis was uncoupled with attenuated fibrotic NASH in Gal-3-deficient mice. HFD-fed WT mice had a higher number of hepatocytes that strongly expressed IL-33 and hepatic CD11b(+)IL-13(+) cells, increased levels of IL-33 and IL-13 and up-regulated IL-33, ST2 and IL-13 mRNA in liver compared with LGALS3(-/-) mice. IL-33 failed to induce ST2 upregulation and IL-13 production by LGALS3(-/-) peritoneal macrophages in vitro. Administration of IL-33 in vivo enhanced liver fibrosis in HFD-fed mice in both genotypes, albeit to a significantly lower extent in LGALS3(-/-) mice, which was associated with less numerous hepatic IL-13-expressing CD11b(+) cells. The present study provides evidence of a novel role for Gal-3 in regulating IL-33-dependent liver fibrosis.

Prognostic value of galectin-3 in patients with heart failure

Galectins are a family of soluble β-galactoside-binding lectins that have important role in inflammation, immunity, and cancer. Galectin-3 as a part of this lectin family plays a very important role in development of heart failure. According to recent papers, galectin-3 plasma level correlates with heart failure outcome, primarily with rehospitalisation and death from heart failure. This paper summarizes the most recent advances in galectin-3 research, with the accent on the role of galectin-3 in pathophysiology of myocardial remodelling and heart failure development--with preserved and reduced ejection fraction, and some implication on development of new disease modifying drugs.

Galectin expression in cancer diagnosis and prognosis: A systematic review

Galectins are a family of proteins that bind to specific glycans thereby deciphering the information captured within the glycome. In the last two decades, several galectin family members have emerged as versatile modulators of tumor progression. This has initiated the development and preclinical assessment of galectin-targeting compounds. With the first compounds now entering clinical trials it is pivotal to gain insight in the diagnostic and prognostic value of galectins in cancer as this will allow a more rational selection of the patients that might benefit most from galectin-targeted therapies. Here, we present a systematic review of galectin expression in human cancer patients. Malignant transformation is frequently associated with altered galectin expression, most notably of galectin-1 and galectin-3. In most cancers, increased galectin-1 expression is associated with poor prognosis while elevated galectin-9 expression is emerging as a marker of favorable disease outcome. The prognostic value of galectin-3 appears to be tumor type dependent and the other galectins require further investigation. Regarding the latter, additional studies using larger patient cohorts are essential to fully unravel the diagnostic and prognostic value of galectin expression. Furthermore, to better compare different findings, consensus should be reached on how to assess galectin expression, not only with regard to localization within the tissue and within cellular compartments but also regarding alternative splicing and genomic variations. Finally, linking galectin expression and function to aberrant glycosylation in cancer cells will improve our understanding of how these versatile proteins can be exploited for diagnostic, prognostic and even therapeutic purposes in cancer patients.

Carbohydrate nanocarriers in biomedical applications: functionalization and construction

Carbohydrates are used to functionalize or construct nanocarriers for biomedical applications – specific targeting, biocompatibility, stealth effect, biodegradability.

Prognostic significance of serum galectin-3 levels in patients with hepatocellular cancer and chronic viral hepatitis

BACKGROUND/AIM

Galectins affect diverse physiological and pathophysiological processes such as development, inflammation, and tumor growth. We aimed to compare serum galectin-3 levels in three patient groups with chronic hepatitis B and C virus (HBV, HCV), cirrhosis secondary to HBV or HCV, and hepatocellular carcinoma (HCC) secondary to HBV or HCV and evaluate the role of galectin-3 during HCC progression.

PATIENTS AND METHODS

Nineteen patients with hepatocellular cancer, 22 patients with cirrhosis, and 24 patients with chronic hepatitis B and C were included in this study. Serum galectin-3 levels in different liver diseases were assessed by enzyme-linked immunosorbent assay.

RESULTS

The mean galectin-3 levels were 4.61 ng/mL (±2.32) in HCC patients, 5.68 ng/mL (±2,2) in cirrhotic patients, 1.98 ng/mL (±1.50) in chronic viral hepatitis group. There were no statistical differences between HCC and cirrhotic patients (P = 0.5), but lower in chronic hepatitis group statistically compared with cirrhosis and HCC (P < 0.001, P = 0.002, respectively). In case of cirrhotic patients, galectin-3 levels were significantly higher in patients with cirrhosis secondary to HCV compared with HBV (P = 0.03). When we evaluated galectin-3 levels in HCC patients, it was found to be 3.92 ng/mL in HCC secondary to hepatitis B and 5.37 ng/mL in HCC secondary to hepatitis C.

CONCLUSION

Serum galectin-3 levels in patients with chronic HBV or HCV may guide us about progression to cirrhosis or HCC and prognosis of the disease. Especially, galectin-3 levels may be more pronounced in case of HCV.

Examination of the regulation of galectin-3 expression in cancer

Galectin-3, a member of a β-galactoside-binding protein family, is involved in normal growth development as well as cancer progression and metastasis, but the detailed mechanisms of its functions or its transcriptional regulations are not well understood. Besides, several regulatory elements such as GC box, CRE motif, AP-1 site, and NF-κB sites, the promoter of galectin-3 gene (LGALS3) contains several CpG islands that can be methylated during tumorigenesis of prostate leading to the gene silencing. Here we describe protocols for identification of galectin-3 DNA methylation, suppression of DNA methyltransferases to reactivate galectin-3 expression, and development of methylation-specific polymerase chain reaction (MS-PCR) to assess galectin-3 expression in various biological specimens such as tissue, serum, and urine samples.

Profiling of concanavalin A-binding glycoproteins in human hepatic stellate cells activated with transforming growth factor-β1

Glycoproteins play important roles in maintaining normal cell functions depending on their glycosylations. Our previous study indicated that the abundance of glycoproteins recognized by concanavalin A (ConA) was increased in human hepatic stellate cells (HSCs) following activation by transforming growth factor-β1 (TGF-β1); however, little is known about the ConA-binding glycoproteins (CBGs) of HSCs. In this study, we employed a targeted glycoproteomics approach using lectin-magnetic particle conjugate-based liquid chromatography-tandem mass spectrometry to compare CBG profiles between LX-2 HSCs with and without activation by TGF-β1, with the aim of discovering novel CBGs and determining their possible roles in activated HSCs. A total of 54 and 77 proteins were identified in the quiescent and activated LX-2 cells, respectively. Of the proteins identified, 14.3% were glycoproteins and 73.3% were novel potential glycoproteins. Molecules involved in protein processing in the endoplasmic reticulum (e.g., calreticulin) and calcium signaling (e.g., 1-phosphatidylinositol-4,5-bisphosphate phosphodiesterase β-2 [PLCB2]) were specifically identified in activated LX-2 cells. Additionally, PLCB2 expression was upregulated in the cytoplasm of the activated LX-2 cells, as well as in the hepatocytes and sinusoidal cells of liver cirrhosis tissues. In conclusion, the results of this study may aid future investigations to find new molecular mechanisms involved in HSC activation and antifibrotic therapeutic targets.

Insights into EPR effect versus lectin-mediated targeted delivery: biodegradable polycarbonate micellar nanoparticles with and without galactose surface decoration

Polymeric micelles with and without galactose are synthesized to study liver targeting ability in an orthotopic HCC rat model. Micelles with galactose accumulate more in the healthy liver tissue instead of HCC, while micelles without galactose amass in HCC by the EPR effect. These micelles show great potential as drug delivery carriers to target either the liver or HCC.

Galectin-3 is associated with a poor prognosis in primary hepatocellular carcinoma

BACKGROUND

Galectin-3, a member of the beta-galactoside-binding lectin family, is a multifunctional protein with various biological functions, including the proliferation and differentiation of tumor cells, angiogenesis, cancer progression, and metastasis. We aimed to clarify if expression of galectin-3 is related to the clinicopathological characteristics and prognosis of hepatocellular carcinoma (HCC) patients, and to explore the possible mechanisms of galectin-3 in hepatocellular carcinoma.

METHODS

First, we investigated galectin-3 mRNA and protein expression by using RT-PCR and Western blotting. Second, tissues from 165 HCC patients were used to evaluate clinicopathological characteristics and prognosis through immunohistochemical analyses. Furthermore, the functions of galectin-3 were analyzed with respect to the proliferation, cell cycle,apoptosis, migration, and invasion of HCC cell lines. Finally, we analyzed galectin-3 expression and micro-vessel density (MVD) by immunohistochemistry (IHC) to find its correlation with angiogenesis in Hepatocellular Carcinoma. Flow cytometer was used to explore apoptosis and Western-blot was used to detect the pathway proteins of apoptosis.

RESULTS

Galectin-3 showed high expression at the mRNA and protein levels in HCC cancer tissues and cell lines. Clinicopathological analyses revealed that increased expression of galectin-3 in tumors was closely associated with a poor prognosis. Galectin-3 knockdown by siRNA significantly inhibited cell growth, migration, and invasion, and induced apoptosis in HCC cells in vitro, whereas galectin-3 overexpression promoted cell growth, migration, and invasion. Correlation analysis of galectin-3 expression and micro-vessel density (MVD) showed that galectin-3 expression in tumor cells stimulates angiogenesis. The observed regulation of cell apoptosis was accompanied by the galectin-3-mediated modulation of caspase3 signaling pathways in HCC cells.

CONCLUSIONS

These data suggest that galectin-3 plays an important part in HCC progression and may serve as a prognostic factor for HCC.

Old and newer biomarkers in heart failure: from pathophysiology to clinical significance

Heart failure is a complex disease in which a careful clinical examination and the measurement of cardiac function may not always be sufficient for making a correct diagnosis. Measuring plasma levels of natriuretic peptides may assist in this process, also offering a good tool for accurate risk stratification. Other alternative biomarkers may give insight into the different pathways of heart failure genesis and pathophysiology, and may help to identify those patients with overt heart failure and a more adverse outcome, or distinguish between those at risk of developing heart failure. Despite a high number of potentially useful biomarkers, only a few will likely be introduced routinely into clinical practice. However, a multi-marker approach might increase the diagnostic accuracy and it might identify different phenotypes of heart failure patients who might benefit from individualized therapy in the future.

Molecular basis for MMP9 induction and disruption of epithelial cell-cell contacts by galectin-3

Dynamic modulation of the physical contacts between neighboring cells is integral to epithelial processes such as tissue repair and cancer dissemination. Induction of matrix metalloproteinase (MMP) activity contributes to the disassembly of intercellular junctions and the degradation of the extracellular matrix, thus mitigating the physical constraint to cell movement. Using the cornea as a model, we show here that a carbohydrate-binding protein, galectin-3, promotes cell-cell detachment and redistribution of the tight junction protein occludin through its N-terminal polymerizing domain. Notably, we demonstrate that galectin-3 initiates cell-cell disassembly by inducing matrix metalloproteinase expression in a manner that is dependent on the interaction with and clustering of the matrix metalloproteinase inducer CD147 (also known as EMMPRIN and basigin) on the cell surface. Using galectin-3-knockout mice in an in vivo model of wound healing, we further show that increased synthesis of MMP9 at the leading edge of migrating epithelium is regulated by galectin-3. These findings establish a new galectin-3-mediated regulatory mechanism for induction of metalloproteinase expression and disruption of cell-cell contacts required for cell motility in migrating epithelia.

Galectin-3 and matrix metalloproteinase-9: Perspective in management of hepatocellular carcinoma

AIM

Hepatocellular carcinoma (HCC) is the fifth most common cancer in men and the seventh in women. HCC varies widely in incidence through the world, with rising incidence in Egypt. This study aimed to estimate the serum levels of matrix metalloproteinase-9 (MMP-9) and its substrate galectin-3 in order to evaluate their diagnostic accuracy and their relation to HCC-related clinical features.

METHODS

For this purpose, serum levels of these biochemical markers were assessed in 50 HCC patients, 30 cirrhotic patients in addition to 10 healthy subjects as a control group using enzyme linked immune-sorbent assay (ELISA).

RESULTS

In the present study, circulating level of galectin-3, MMP-9 increased significantly in HCC as compared to the control group (P = 0.044 and 0.04, respectively). However, no significant difference was observed between cirrhotic and HCC patients (P = 0.231 and 0.193, respectively). Our study found that HCC patients with metastatic spread had a significant elevation of both serum galectin-3 and MMP-9 levels (P = 0.028 and <0.0001, respectively). In addition, galectin-3 level significantly increased in HCC patients with poor prognosis suffering from portal vein invasion (P = 0.014). Moreover, MMP-9 increased significantly with increasing stage of Barcelona-Clinic Liver Cancer Group diagnostic and treatment strategy (P = 0.01).

CONCLUSION

MMP-9 and galectin-3 could be used as a guide for prognosis of HCC since they may play a role in HCC progression and metastasis. However, they are not useful markers for HCC diagnosis.

Nicotine promotes apoptosis resistance of breast cancer cells and enrichment of side population cells with cancer stem cell-like properties via a signaling cascade involving galectin-3, α9 nicotinic acetylcholine receptor and STAT3

Nicotine, a main addictive compound in tobacco smoke, has been linked to promotion and progression of lung, head and neck, pancreatic, and breast cancers, but the detailed mechanisms of cancer progression remain elusive. Here, we show that nicotine induces the expression of galectin-3 (an anti-apoptotic β-galactoside-binding lectin) in breast cancer cell line and in primary tumors from breast cancer patients. Nicotine-induced up regulation of galectin-3 is due to an increased expression of α9 isoform of nicotinic acetylcholine receptor (α9nAChR), which activates transcription factor STAT3 that in turn, physically binds to galectin-3 (LGALS3) promoter and induces transcription of galectin-3. Intracellular galectin-3 increased mitochondrial integrity and suppressed chemotherapeutic-induced apoptosis of breast cancer cell. Moreover, nicotine-induced enrichment of side population cells with cancer stem cell-like properties was modulated by galectin-3 expression and could be significantly reduced by transient knock down of LGALS3 and its upstream signaling molecules STAT3 and α9nAChR. Thus, galectin-3 or its upstream signaling molecule STAT3 or α9nAChR could be a potential target to prevent nicotine-induced chemoresistance in breast cancer.

Therapeutic targets in heart failure: refocusing on the myocardial interstitium

New therapeutic targets, agents, and strategies are needed to prevent and treat heart failure (HF) after a decade of failed research efforts to improve long-term patient outcomes, especially in patients after hospitalization for HF. Conceptually, an accurate assessment of left ventricular structure is an essential step in the development of novel therapies because heterogeneous pathophysiologies underlie chronic HF and hospitalization for HF. Improved left ventricular characterization permits the identification and targeting of the intrinsic fundamental disease-modifying pathways that culminate in HF. Interstitial heart disease is one such pathway, characterized by extracellular matrix (ECM) expansion that is associated with mechanical, electrical, and vasomotor dysfunction and adverse outcomes. Previous landmark trials that appear to treat interstitial heart disease were effective in improving outcomes. Advances in cardiovascular magnetic resonance now enable clinicians and researchers to assess the interstitium and quantify ECM expansion using extracellular volume fraction measures and other derangements in cardiovascular structure. These capabilities may provide a mechanistic platform to advance understanding of the role of the ECM, foster the development of novel therapeutics, and target specific disease-modifying pathways intrinsic to the ventricle. Refocusing on the interstitium may potentially improve care through the identification and targeted treatment of key patient subgroups.

Galectin-3 in cancer

Galectin-3 (Gal-3) plays important roles in cell proliferation, adhesion, differentiation, angiogenesis and apoptosis in normal and pathologic tissues. Accumulated evidences indicate that Gal-3 is closely involved in tumor cell transformation, migration, invasion and metastasis. In this review, the associations of the expression and localization of Gal-3 as well as its potential action mechanism in tumorigenesis in a variety of cancers were summarized and concluded. Gal-3 is gaining its attraction as a potential new biomarker for the diagnosis, treatment and prognosis of certain tumors.

Protective effects of silymarin on fumonisin B₁-induced hepatotoxicity in mice

The present study was conducted to investigate the effect of silymarin on experimental liver toxication induced by Fumonisin B₁ (FB₁) in BALB/c mice. The mice were divided into six groups (n = 15). Group 1 served as the control. Group 2 was the silymarin control (100 mg/kg by gavage). Groups 3 and 4 were treated with FB₁ (Group 3, 1.5 mg/kg FB₁, intraperitoneally; and Group 4, 4.5 mg/kg FB₁). Group 5 received FB₁ (1.5 mg/kg) and silymarin (100 mg/kg), and Group 6 was given a higher dose of FB₁ (4.5 mg/kg FB₁) with silymarin (100 mg/kg). Silymarin treatment significantly decreased (p < 0.0001) the apoptotic rate. FB₁ administration significantly increased (p < 0.0001) proliferating cell nuclear antigen and Ki-67 expression. Furthermore, FB₁ elevated the levels of caspase-8 and tumor necrosis factor-alpha mediators while silymarin significantly reduced (p < 0.0001) the expression of these factors. Vascular endothelial growth factor (VEGF) and fibroblast growth factor-2 (FGF-2) expressions were significantly elevated in Group 4 (p < 0.0001). Silymarin administration alleviated increased VEGF and FGF-2 expression levels (p < 0.0001). In conclusion, silymarin ameliorated toxic liver damage caused by FB₁ in BALB/c mice.

De novo galectin-3 expression influences the response of melanoma cells to isatin-Schiff base copper (II) complex-induced oxidative stimulus

Galectin-3, a ubiquitous member of the galectin family, has been shown to control cellular proliferation, adhesion, migration and apoptosis; thus, it has a role in tumor development and progression. Galectin-3 expression is both up- and down-regulated during melanoma progression. However, conflicting data regarding its roles in tumor biology prompted us to investigate if the presence of galectin-3 influences the response of melanoma cells to a novel metallodrug because metastatic melanoma acquires chemo resistance and is reported to be redox-sensitive. Previously, it was demonstrated that the complex [bis-(2-oxindol-3-yl-imino)-2-(2-aminoethyl) pyridine-N,N'] copper (II) perchlorate, herein referred to as [Cu(isaepy)], induces ROS formation and apoptosis in neuroblastoma cells through mitochondrial uncoupling and the activation of AMPK/p38/p53 signaling. Here, we used a model of vertical growth melanoma (TM1), in which GAL3 expression is lost during tumor progression. When de novo expressed, galectin-3 was found to be ubiquitously present in all subcellular compartments. Our results demonstrate that de novo galectin-3 expression impairs the cellular antioxidant system and renders TM1G3 cells more susceptible than GAL3-null TM1MNG3 cells to [Cu(isaepy)] treatment. This compound, in contrast with the redox inactive [dichloro (2-oxindol-3-yl-imino)-2-(2-aminoethyl) pyridine-N,N'] zinc (II), herein referred to as [Zn(isaepy)], leads to increased intracellular ROS accumulation, increased carbonyl stress, increased mitochondrial depolarization, decreased cell adhesion, increased p38 activation and apoptosis in TM1G3, compared with TM1MNG3. Cell death was shown to be dependent on a hydrogen peroxide-derived species and on the activation of p38. Because mitochondria are a target of both [Cu(isaepy)] and galectin-3, we propose that the presence of galectin-3 in this organelle favors increased ROS production, thereby inducing oxidative cellular damage and apoptotic death. Therefore, [Cu(isaepy)] may be envisaged as a possible anti-melanoma strategy, particularly for melanomas that express galectin-3.

Clear cell carcinomas of the ovary: a multi-institutional study of 129 cases in Korea with prognostic significance of Emi1 and Galectin-3

Accurate diagnosis of ovarian clear cell carcinoma (CCC) is important because of its poor prognosis with chemoresistance and a high recurrent rate. The clinicopathologic characteristics and prognostic significance of the cell cycle regulator [early mitotic inhibitor-1 (Emi1)] and galactoside-binding protein (Galectin-3) were evaluated. Among 155 CCCs from 18 hospitals in Korea between 1995 and 2006, 129 pure CCCs were selected with consensus using immunohistochemical stains for hepatocyte nuclear factor-1β, Wilms' tumor protein, and estrogen receptor. The expressions of Emi1, Galectin-3, p53, and Ki-67 labeling index were analyzed with clinicopathologic parameters and the patient's survival. The mean age of the patients was 49.6 yr; the tumors were bilateral in 10.9%, and the average size was 12 cm. Adenofibromatous component was found in 7%, and endometriosis in 48.1% of the cases. Psammoma body was seen in 16.3%. Disease-free survival and overall survival rates were 78.3% and 79.1%, respectively. The International Federation of Obstetrics and Gynecology (FIGO) stage was the most important prognostic indicator. Emi1 expression (>5%) was seen in 23.3% of CCCs, and associated with high FIGO grades and poor overall survival (P<0.05). High Galectin-3 (≥80%) expression was seen in 59.7% of CCCs, and associated with FIGO stages III and IV, and high Ki-67 labeling index. High Ki-67 labeling index (≥50%) and p53 expression (≥50%) were seen in 27.1% and 18.6% of CCCs, respectively, but there was no clinicopathologic and prognostic significance. On the basis of the fact that the expression of Emi1 in CCC was correlated with a high histologic grade and worse overall survival, target therapy using inhibitors of Emi1 may be tried in the management of CCC patients with Emi1 expression.

Elevated galectin-3 precedes the development of CKD

Galectin-3, a profibrotic mediator, is linked to the development of renal fibrosis in animal models and inversely correlates with GFR in humans, but whether galectin-3 predicts incident kidney disease is unknown. Here, we assessed renal outcomes for 2450 Framingham Offspring participants who attended examination 6 (1995-1998) and had follow-up data at examination 8 (2005-2008). Renal outcomes of interest included rapid decline in renal function (≥3 ml/min per 1.73 m(2) per year decline in estimated GFR [eGFR]), CKD (eGFR < 60 ml/min per 1.73 m(2)), and albuminuria (albumin-to-creatinine ratio ≥17 mg/g in men or ≥25 mg/g in women). We used multivariable logistic regression models to evaluate associations between galectin-3 with incident renal outcomes at examination 8. During a mean follow-up of 10.1 years, GFR declined rapidly in 241 (9.2%) participants, incident CKD developed in 277 (11.3%), and albuminuria developed in 194 (10.1%). Higher plasma levels of galectin-3 were associated with rapid decline in eGFR (per 1-SD log-galectin-3; adjusted odds ratio [OR], 1.49; 95% confidence interval [CI], 1.28 to 1.73]) and a higher risk of incident CKD (OR, 1.47; 95% CI, 1.27 to 1.71), but not with the risk of incident albuminuria. The addition of galectin-3 to clinical predictors improved the C-statistic (0.837-0.845; P=0.02) but did not reach predefined thresholds for clinically significant improvements to risk prediction based on reclassification indices. In conclusion, elevated levels of plasma galectin-3 are associated with increased risks of rapid GFR decline and of incident CKD in the community, which calls for further study in higher-risk groups.

Personalizing biomarker strategies in heart failure with galectin-3

Heart failure is a leading cause of death and disability. Galectin-3 expression is associated with myocardial fibrosis; recombinant galectin-3 can induce myocardial fibrosis in experimental animals. However, the fact that endogenous galectin-3 is causative of myocardial fibrosis is yet to be firmly established. Nevertheless, the important discovery that N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP), a naturally occurring anti-inflammatory and antifibrotic peptide, inhibits galectin-3 expression, which prevents cardiac remodeling and dysfunction, provides impetus for translational research into anti-galectin therapy. The lack of a close relationship between galectin-3 and brain natriuretic peptide creates the possibility of a complimentary role. Thus, whilst brain natriuretic peptide is a useful biomarker for diagnosing heart failure, galectin-3 appears to be a culprit biomarker that mediates the development of heart failure, raising the possibility that specific anti-galectin therapy may halt the development of heart failure. Furthermore, data are beginning to emerge supporting the hypothesis that galectin-3 is crucial in the angiotensin–aldosterone pathway leading to salt and water retention, a key mechanism which can result in the development of heart failure. Thus, one might expect patients with heart failure and raised levels of galectin-3 to benefit from aldosterone antagonist therapy. Numerous clinical trials have already established the role of galectin-3 in predicting response to heart failure management, in particular how high levels of galectin-3 predicts mortality. A recent post hoc analysis of the Controlled Rosuvastatin Multinational Trial in Heart Failure (CORONA) suggested that patients with relatively low galectin-3 levels (<19 ng/ml) are most likely to benefit from statin therapy. This generated an important hypothesis that deserves further study.

Galectin-3, a marker of cardiac fibrosis, predicts incident heart failure in the community

OBJECTIVES

The aim of this study was to examine the relation of galectin-3 (Gal-3), a marker of cardiac fibrosis, with incident heart failure (HF) in the community.

BACKGROUND

Gal-3 is an emerging prognostic biomarker in HF, and experimental studies suggest that Gal-3 is an important mediator of cardiac fibrosis. Whether elevated Gal-3 concentrations precede the development of HF is unknown.

METHODS

Gal-3 concentrations were measured in 3,353 participants in the Framingham Offspring Cohort (mean age 59 years; 53% women). The relation of Gal-3 to incident HF was assessed using proportional hazards regression.

RESULTS

Gal-3 was associated with increased left ventricular mass in age-adjusted and sex-adjusted analyses (p = 0.001); this association was attenuated in multivariate analyses (p = 0.06). A total of 166 participants developed incident HF and 468 died during a mean follow-up period of 11.2 years. Gal-3 was associated with risk for incident HF (hazard ratio [HR]: 1.28 per 1 SD increase in log Gal-3; 95% confidence interval [CI]: 1.14 to 1.43; p < 0.0001) and remained significant after adjustment for clinical variables and B-type natriuretic peptide (HR: 1.23; 95% CI: 1.04 to 1.47; p = 0.02). Gal-3 was also associated with risk for all-cause mortality (multivariable-adjusted HR: 1.15; 95% CI: 1.04 to 1.28; p = 0.01). The addition of Gal-3 to clinical factors resulted in negligible changes to the C-statistic and minor improvements in net reclassification improvement.

CONCLUSIONS

Higher concentration of Gal-3, a marker of cardiac fibrosis, is associated with increased risk for incident HF and mortality. Future studies evaluating the role of Gal-3 in cardiac remodeling may provide further insights into the role of Gal-3 in the pathophysiology of HF.

Microarray expression analysis and identification of serum biomarkers for Niemann-Pick disease, type C1

Niemann-Pick disease type C (NPC) is a lysosomal storage disorder characterized by liver disease and progressive neurodegeneration. Deficiency of either NPC1 or NPC2 leads to the accumulation of cholesterol and glycosphingolipids in late endosomes and early lysosomes. In order to identify pathological mechanisms underlying NPC and uncover potential biomarkers, we characterized liver gene expression changes in an Npc1 mouse model at six ages spanning the pathological progression of the disease. We identified altered gene expression at all ages, including changes in asymptomatic, 1-week-old mice. Biological pathways showing early altered gene expression included: lipid metabolism, cytochrome P450 enzymes involved in arachidonic acid and drug metabolism, inflammation and immune responses, mitogen-activated protein kinase and G-protein signaling, cell cycle regulation, cell adhesion and cytoskeleton remodeling. In contrast, apoptosis and oxidative stress appeared to be late pathological processes. To identify potential biomarkers that could facilitate monitoring of disease progression, we focused on a subset of 103 differentially expressed genes that encode secreted proteins. Further analysis identified two secreted proteins with increased serum levels in NPC1 patients: galectin-3 (LGALS3), a pro-inflammatory molecule, and cathepsin D (CTSD), a lysosomal aspartic protease. Elevated serum levels of both proteins correlated with neurological disease severity and appeared to be specific for NPC1. Expression of Lgals3 and Ctsd was normalized following treatment with 2-hydroxypropyl-β-cyclodextrin, a therapy that reduces pathological findings and significantly increases Npc1(-/-) survival. Both LGALS3 and CTSD have the potential to aid in diagnosis and serve as biomarkers to monitor efficacy in therapeutic trials.

Deficiency in galectin-3 promotes hepatic injury in CDAA diet-induced nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is increasingly recognized as a condition in which excess fat accumulates in hepatocytes. Nonalcoholic steatohepatitis (NASH), a severe form of NAFLD in which inflammation and fibrosis in the liver are noted, may eventually progress to end-stage liver disease. Galectin-3, a β-galactoside-binding animal lectin, is a multifunctional protein. This protein is involved in inflammatory responses and carcinogenesis. We investigated whether galectin-3 is involved in the development of NASH by comparing galectin-3 knockout (gal3(-/-)) mice and wild-type (gal3(+/+)) mice with choline-deficient L-amino-acid-defined (CDAA) diet-induced NAFLD/NASH. Hepatic injury was significantly more severe in the gal3(-/-) male mice, as compared to the gal3(+/+) mice. Data generated by microarray analysis of gene expression suggested that galectin-3 deficiency causes alterations in the expression of various genes associated with carcinogenesis and lipid metabolism. Through canonical pathway analysis, involvement of PDGF and IL-6 signaling pathways was suggested in galectin-3 deficiency. Significant increase of CD14, Fos, and Jun, those that were related to lipopolysaccharide-mediated signaling, was candidate to promote hepatocellular damages in galectin-3 deficiency. In conclusion, galectin-3 deficiency in CDAA diet promotes NAFLD features. It may be caused by alterations in the expression profiles of various hepatic genes including lipopolysaccharide-mediated inflammation.

Galectin-3 modulates phagocytosis-induced stellate cell activation and liver fibrosis in vivo

Hepatic stellate cells (HSC), the key fibrogenic cells of the liver, transdifferentiate into myofibroblasts upon phagocytosis of apoptotic hepatocytes. Galectin-3, a β-galactoside-binding lectin, is a regulator of the phagocytic process. In this study, our aim was to study the mechanism by which extracellular galectin-3 modulates HSC phagocytosis and activation. The role of galectin-3 in engulfment was evaluated by phagocytosis and integrin binding assays in primary HSC. Galectin-3 expression was studied by real-time PCR and enzyme-linked immunosorbent assay, and in vivo studies were done in wild-type and galectin-3(-/-) mice. We found that HSC from galectin-3(-/-) mice displayed decreased phagocytic activity, expression of transforming growth factor-β1, and procollagen α1(I). Recombinant galectin-3 reversed this defect, suggesting that extracellular galectin-3 is required for HSC activation. Galectin-3 facilitated the α(v)β(3) heterodimer-dependent binding, indicating that galectin-3 modulates HSC phagocytosis via cross-linking this integrin and enhancing the tethering of apoptotic cells. Blocking integrin α(v)β(3) resulted in decreased phagocytosis. Galectin-3 expression and release were induced in active HSC engulfing apoptotic cells, and this was mediated by the nuclear factor-κB signaling. The upregulation of galectin-3 in active HSC was further confirmed in vivo in bile duct-ligated (BDL) rats. Galectin-3(-/-) mice displayed significantly decreased fibrosis, with reduced expression of α-smooth muscle actin and procollagen α1(I) following BDL. In summary, extracellular galectin-3 plays a key role in liver fibrosis by mediating HSC phagocytosis, activation, and subsequent autocrine and paracrine signaling by a feedforward mechanism.

Identification of galectin-1 and galectin-3 as novel partners for von Willebrand factor

OBJECTIVE

Although von Willebrand factor (VWF) is a heavily glycosylated protein, its potential to associate with glycan-binding proteins is poorly investigated. Here, we explored its interaction with the glycan-binding proteins galectin-1 and galectin-3.

METHODS AND RESULTS

Immunofluorescence analysis using Duolink proximity ligation assays revealed that VWF colocalizes with galectin-1 and galectin-3 in endothelial cells, both before and after stimulation of endothelial cells. Moreover, galectin-1 was found along the typical VWF bundles that are released by endothelial cells. Galectin-1 and galectin-3 could be coprecipitated with VWF from plasma in immunoprecipitation assays, whereas plasma levels of galectin-1 and galectin-3 were significantly reduced in VWF-deficient mice. Binding studies using purified proteins confirmed that VWF could directly interact with both galectins, predominantly via its N-linked glycans. In search of the physiological relevance of the VWF-galectin interaction, we found that inhibition of galectins in in vitro perfusion assays was associated with increased VWF-platelet string formation, a phenomenon that was reproduced in galectin-1/galectin-3 double-deficient mice. These mice were also characterized by a more rapid formation of initial thrombi following ferric chloride-induced injury.

CONCLUSIONS

We have identified galectin-1 and galectin-3 as novel partners for VWF, and these proteins may modulate VWF-mediated thrombus formation.

Galectin-3 and the development of heart failure after acute coronary syndrome: pilot experience from PROVE IT-TIMI 22

BACKGROUND

Galectin-3 is a β-galactoside-binding lectin that has been implicated in cardiac fibrosis and remodeling, is increased in models of failure-prone hearts, and has prognostic value in patients with heart failure (HF). The relationship between galectin-3 and the development of HF after acute coronary syndrome (ACS) is unknown.

METHODS

In a nested case-control study among patients with ACS in PROVE IT-TIMI 22, we identified 100 cases with a hospitalization for new or worsening HF. Controls were matched (1:1) for age, sex, ACS type, and randomized treatment. Serum galectin-3 was measured at baseline (within 7 days post-ACS).

RESULTS

Patients who developed HF had higher baseline galectin-3 [median 16.7 μg/L (25th, 75th percentile 14.0, 20.6) vs 14.6 μg/L (12.0, 17.6), P=0.004]. Patients with baseline galectin-3 above the median had an odds ratio of 2.1 (95% CI 1.2-3.6) for developing HF, P=0.010. Galectin-3 showed a graded relationship with risk of HF. Cases were more likely to have hypertension, diabetes, prior MI, and prior HF; after adjustment for these factors, this graded relationship with galectin-3 quartile and HF remained significant [adjusted OR 1.4 (95% CI 1.1-1.9), P=0.020]. When BNP was added to the model, the relationship between galectin-3 and HF was attenuated [adjusted OR 1.3 (95% CI: 0.96-1.9), P=0.08].

CONCLUSIONS

The finding that galectin-3 is associated with the risk of developing HF following ACS adds to emerging evidence supporting galectin-3 as a biomarker of adverse remodeling contributing to HF as well as a potential therapeutic target.

Cell surface glycan-lectin interactions in tumor metastasis

The development of secondary cancers, metastases, requires that a multitude of events are completed in an ordered and sequential manner. This review focuses on the role of cell surface glycans and their binding partners in the metastatic process. A common feature of metastasis is that the steps require adhesive interactions; many of these are mediated by cell surface glycans and their interactions with endogenous carbohydrate binding proteins (lectins). Aberrant glycosylation is a key feature of malignant transformation and the glycans involved influence the adhesive interactions of cancer cells often providing favorable conditions for tumor dissemination. This review focuses on glycans on the cancer cell surface and their association with endogenous lectins. In particular, E-cadherin and siglec-mediated disaggregation of tumor cells from the primary tumor mass; integrins, laminin and CD44-mediated invasion and migration of tumor cells through the connective tissue; the involvement of heparan sulphate in tumor angiogenesis and C-/S-type lectin interactions with the vasculature. The potential role of glycans in cancer cell evasion of immune surveillance is considered.

Evidence of heavy methylation in the galectin 3 promoter in early stages of prostate adenocarcinoma: development and validation of a methylated marker for early diagnosis of prostate cancer

Galectins, soluble intracellular and extracellular beta-galactoside-binding proteins, are known to be involved in the progression and metastasis of various cancers, including prostate adenocarcinoma, but the detailed mechanism of their biological roles remains elusive. In the prostate cancer cell lines PC-3 and DU-145, galectin 3 (gal3) is present at normal levels, whereas in LNCaP, its expression is silenced. In LNCaP, the gal3 promoter was heavily methylated, whereas PC-3 or DU-145 cells showed negligible or no methylation in the gal3 promoter indicating a negative correlation between gal3 promoter methylation and its expression. On immunohistochemical analysis of normal and tumor prostate tissues, gal3 was found expressed both in nucleus and cytoplasm of benign prostatic hyperplasia, high-grade prostatic intraepithelial neoplasia, and stage I. The expression of the gal3 was found drastically downregulated in advanced stages and, interestingly, mostly in the cytoplasm. On methylation analysis, the gal3 promoter in stage II prostate adenocarcinoma (PCa) was found heavily methylated, whereas in stages III and IV, it was only lightly methylated. However, in stage I PCa, both heavy and light methylations were observed in the gal3 promoter. In normal and benign prostatic hyperplasia tissues, the gal3 promoter was almost unmethylated. The differential cytosine methylation in the gal3 promoter in stages I to IV PCa enabled us to develop and validate a methylation-specific polymerase chain reaction-based sensitive assay specific for stages I and II PCa. These stages are considered the critical stages for successful intervention, thus underscoring the significance of this diagnostic assay.

Galectin-3 protein modulates cell surface expression and activation of vascular endothelial growth factor receptor 2 in human endothelial cells

Angiogenesis is heavily influenced by VEGF-A and its family of receptors, particularly VEGF receptor 2 (VEGF-R2). Like most cell surface proteins, VEGF-R2 is glycosylated, although the function of VEGF-R2 with respect to its glycosylation pattern is poorly characterized. Galectin-3, a glycan binding protein, interacts with the EGF and TGFβ receptors, retaining them on the plasma membrane and altering their signal transduction. Because VEGF-R2 is glycosylated and both galectin-3 and VEGF-R2 are involved with angiogenesis, we hypothesized that galectin-3 binds VEGF-R2 and modulates its signal transduction as well. Employing a Western blot analysis approach, we found that galectin-3 induces phosphorylation of VEGF-R2 in endothelial cells. Knockdown of galectin-3 and Mgat5, an enzyme that synthesizes high-affinity glycan ligands of galectin-3, reduced VEGF-A mediated angiogenesis in vitro. A direct interaction on the plasma membrane was detected between galectin-3 and VEGF-R2, and this interaction was dependent on the expression of Mgat5. Using immunofluorescence and cell surface labeling, we found an increase in the level of internalized VEGF-R2 in both Mgat5 and galectin-3 knockdown cells, suggesting that galectin-3 retains the receptor on the plasma membrane. Finally, we observed reduced suture-induced neovascularization in the corneas of Gal3(-/-) and Mgat5(-/-) mice. These findings are consistent with the hypothesis that, like its role with the EGF and TGFβ receptors, galectin-3 contributes to the plasma membrane retention and proangiogenic function of VEGF-R2.

Systemic and hepatic vein galectin-3 are increased in patients with alcoholic liver cirrhosis and negatively correlate with liver function

Recently we demonstrated higher galectin-3 in portal venous serum (PVS) compared to hepatic venous serum (HVS) in a small cohort of patients with normal liver function suggesting hepatic removal of galectin-3. Here, galectin-3 was measured by ELISA in PVS, HVS and systemic venous blood (SVS) of 33 patients with alcoholic liver cirrhosis and a larger cohort of 11 patients with normal liver function. Galectin-3 was cleared by the healthy but not the cirrhotic liver, and subsequently HVS and SVS galectin-3 levels were significantly increased in the patients with liver cirrhosis compared to controls. In healthy liver galectin-3 was produced by cholangiocytes and synthesis by hepatocytes was only observed in cirrhotic liver. Hepatic venous pressure gradient did not correlate with galectin-3 levels excluding hepatic shunting as the principal cause of higher SVS galectin-3. Galectin-3 was elevated in all blood compartments of patients with CHILD-PUGH stage C compared to patients with CHILD-PUGH stage A, and was higher in patients with ascites than patients without this complication. Galectin-3 was negatively associated with antithrombin-3 whose synthesis is reduced with worse liver function. Galectin-3 positively correlated with urea and creatinine, and PVS galectin-3 showed a negative association with creatinine clearance as an accepted measure of kidney function. To summarize in the current study systemic, portal and hepatic levels of galectin-3 were found to be negatively associated with liver function in patients with alcoholic liver cirrhosis and this may in part be related to impaired hepatic removal and/or increased synthesis in cirrhotic liver.

Comprehensive analysis of cellular galectin-3 reveals no consistent oncogenic function in pancreatic cancer cells

Galectin-3 (Gal-3), a 31 kDa member of the family of beta-galactoside-binding proteins, has been implicated in the progression of different human cancers. However, the proposed roles differ widely, ranging from tumor-promoting cellular functions and negative impact on patient prognosis to tumor-suppressive properties and positive prognostic impact. We and others have previously identified Gal-3 as overexpressed in pancreatic cancer as compared to chronic pancreatitis and normal pancreatic tissue. The purpose of this study was thus the comprehensive analysis of putative cellular functions of Gal-3 by transient as well as stable silencing or overexpression of Gal-3 in a panel of 6 well-established pancreatic cancer cell lines. Our results confirm that galectin-3 is upregulated at the mRNA level in pancreatic cancer and strongly expressed in the majority of pancreatic cancer cell lines. In individual cell lines, transient knockdown of Gal-3 expression resulted in moderate inhibitory effects on proliferation, migration or anchorage-independent growth of the cells, but these effects were not consistent across the spectrum of analyzed cell lines. Moreover, functional effects of the modulation of Gal-3 expression were not observed in stable knockdown or overexpression approaches in vitro and did not alter the growth characteristics of nude mouse xenograft tumors in vivo. Our data thus do not support a direct functional role of Gal-3 in the malignant transformation of pancreatic epithelial cells, although paracrine or systemic effects of Gal-3 expression are not excluded.

Novel roles of galectin-1 in hepatocellular carcinoma cell adhesion, polarization, and in vivo tumor growth

Galectin-1 (Gal-1), a widely expressed β-galactoside-binding protein, exerts pleiotropic biological functions. Gal-1 is up-regulated in hepatocarcinoma cells, although its role in liver pathophysiology remains uncertain. We investigated the effects of Gal-1 on HepG2 hepatocellular carcinoma (HCC) cell adhesion and polarization. Soluble and immobilized recombinant Gal-1 (rGal-1) promoted HepG2 cell adhesion to uncoated plates and also increased adhesion to laminin. Antibody-mediated blockade experiments revealed the involvement of different integrins as critical mediators of these biological effects. In addition, exposure to rGal-1 markedly accelerated the development of apical bile canaliculi as shown by TRITC-phalloidin labeling and immunostaining for multidrug resistance associated-protein 2 (MRP2). Notably, rGal-1 did not interfere with multidrug resistance protein 1/P-glycoprotein or MRP2 apical localization, neither with transfer nor secretion of 5-chloromethylfluorescein diacetate through MRP2. Stimulation of cell adhesion and polarization by rGal-1 was abrogated in the presence of thiodigalactoside, a galectin-specific sugar, suggesting the involvement of protein-carbohydrate interactions in these effects. Additionally, Gal-1 effects were abrogated in the presence of wortmmanin, PD98059 or H89, suggesting involvement of phosphoinositide 3-kinase (PI3K), mitogen-activated protein kinase and cyclic adenosine monophosphate-dependent protein kinase signaling pathways in these functions. Finally, expression levels of this endogenous lectin correlated with HCC cell adhesion and polarization and up-regulation of Gal-1-favored growth of hepatocarcinoma in vivo.

CONCLUSION

Our results provide the first evidence of a role of Gal-1 in modulating HCC cell adhesion, polarization, and in vivo tumor growth, with critical implications in liver pathophysiology.

Modified apple polysaccharide prevents against tumorigenesis in a mouse model of colitis-associated colon cancer: role of galectin-3 and apoptosis in cancer prevention

BACKGROUND

Colorectal cancer (CRC) is one of the most common and preventable cancers. Regular consumption of apples is conducive to reduction in CRC risk.

AIM OF THE STUDY

To evaluate effects of modified apple polysaccharide (MAP) on tumorigenesis in a mouse model of colitis-associated colon cancer.

METHODS

One hundred male ICR mice were administered with 1, 2-dimethyl-hydrazine (DMH) and dextran sodium sulfate (DSS). Forty mice were given no further treatment, the rest were fed basal diet blended with three different doses of MAP; 2.5, 5, and 10% (20 mice in each group).

RESULTS

MAP significantly protected ICR mice against DMH/DSS-induced tumorigenesis. The incidence of tumor development was 90% (18/20) in the mice treated with DMH/DSS, but that was reduced to 25% (5/20), 15% (3/20), and 5% (1/20), respectively, in the mice treated with basal diets plus 2.5, 5, and 10% of MAP. Study of apoptosis of colonic epithelial cells revealed that MAP moderately increased apoptosis, suggesting that the anti-tumor potency of MAP was probably attributed to its ability to induce apoptosis. Western blot analysis demonstrated that carbohydrate-binding protein galectin-3 changed in both the nucleus and the cytoplasm during the process from colitis to colon cancer in the model. And MAP could inhibit the binding of galectin-3 to its ligand: this is, at least in part, the possible mechanism of MAP by enhancing apoptosis and preventing tumorigenesis.

CONCLUSIONS

These data suggest that MAP has a potential role in clinical prevention and treatment for colon cancer.

Galectin-3 in cardiac remodeling and heart failure

Galectin-3 is a member of the galectin family, which consists of animal lectins that bind β-galactosides. Recently, a role for galectin-3 in the pathophysiology of heart failure has been suggested. It was observed that galectin-3 is specifically upregulated in decompensated heart failure compared with compensated heart failure in animal models of heart failure. This has been associated with activation of fibroblasts and macrophages, which are a hallmark of cardiac remodeling. Therefore, galectin-3 may be a culprit biomarker in heart failure. Initial clinical observations indicate that galectin-3 may be a useful biomarker for decompensated heart failure, with incremental value over well-used “pressure-dependent” biomarkers, such as B-type natriuretic peptide. Future studies should focus on galectin-3 biology to better address the usefulness of galectin-3 as a biomarker and probe the usefulness of anti-galectin-3 therapy in treating heart failure.

Identification of proteins differentially expressed between capillary endothelial cells of hepatocellular carcinoma and normal liver in an orthotopic rat tumor model using 2-D DIGE

Hepatocellular carcinoma (HCC) is one of the deadliest cancers with few treatment options. It is a hypervascular tumor in which angiogenesis plays a critical role in its progression. Tumor capillary endothelial cells (TECs) in HCC are known to originate from liver sinusoid endothelial cells, which then go through a capillarization process to become morphologically as well as functionally different TECs. In this work, we investigated proteins differentially expressed between freshly isolated TECs and sinusoid endothelial cells from well-formed rat HCC using 2-D DIGE coupled with MALDI-TOF/TOF MS. Thirty-eight unique proteins were identified to be differentially expressed more than twofold between the two endothelial cell types. Amongst the differentially expressed proteins, two novel endothelial markers, EH domain-containing protein 3 and galectin-3, were confirmed by Western blot and immunohistochemistry in both rat and human HCC samples. We showed that EH domain-containing protein 3 is significantly down-regulated in TECs, but galectin-3 is up-regulated. We propose possible roles of these two proteins in tumor vessel development in HCC.

Implication of the Galectin-3 in colorectal cancer development (about 325 Tunisian patients)

Galectin-3 is a specific soluble lectin of the beta-galactoside family. It plays an important role in cell adherence, proliferation, and differentiation. It has also been shown that galectin-3 expression correlates with tumor progression in several types of cancers. We investigated the involvement of galectin-3 in colorectal cancer development. We performed a comparative immunohistochemical analysis of galectin-3 expression in term of intensity and distribution in normal mucosa, in primary tumor and in metastasis from 200 patients with colorectal cancer selected among 325 cases. We also compared the galectin-3 staining according to the histological subtype (mucinous vs non mucinous), tumoral differentiation and stage of tumor. We showed a strong and diffuse positive staining of galectin-3 in both adjacent and distanced normal mucosa, in well differentiated adenocarcinoma and in metastasis. However, we note a progressive decrease of galectin-3 staining according to the decreasing degree of tumoral differentiation. We also observed a loss of this protein in adenocarcinoma with mucinous component < 50%, where the positive staining was limited only to the well differentiated areas of tumor. These data suggest that galectin-3 play an important role in colorectal cancer progression concerning the non mucinous carcinoma and can be used as a prognostic factor to predict poor outcome of patients. In mucinous subtype, galectin-3 might be implicated in one or many step of its genesis perhaps through the control of cellular adhesion and interaction with mucin produced. Adenocarcinoma with mucinous component <50% would be integrate to mucinous carcinoma, not to non mucinous ones. These investigations could open perspectives for therapeutic means targeted to improve the prognosis of this neoplasm.

Serum galectin-3 is elevated in obesity and negatively correlates with glycosylated hemoglobin in type 2 diabetes

CONTEXT

Adipocytes synthesize galectin-3 whose deficiency protects from inflammation associated with metabolic diseases. We aimed to study circulating galectin-3 in obesity and type 2 diabetes (T2D).

STUDY DESIGN

Galectin-3 was measured by ELISA in the serum of male normal-weight and overweight controls and T2D patients and in T2D patients of both sexes. Because visceral fat contributes to systemic inflammation, galectin-3 was analyzed in paired samples of human and rodent sc and visceral adipose tissue. Visceral adipose tissue adipokines are released to the portal vein, and galectin-3 was analyzed in portal, hepatic, and systemic venous serum (PVS, HVS, and SVS, respectively) of patients with liver cirrhosis and in patients who underwent surgery for nonhepatic diseases. The effect of metformin on adipocyte galectin-3 was analyzed by immunoblot.

RESULTS

Circulating galectin-3 was similarly elevated in T2D and obesity compared with normal-weight individuals and revealed a body mass index-dependent positive correlation with leptin, resistin, IL-6, and age. In T2D patients, galectin-3 was increased in serum of patients with elevated C-reactive protein and negatively correlated with glycated hemoglobin. Metformin treatment was associated with lower systemic galectin-3. Reduced galectin-3 in metformin-incubated human adipocytes indicated that low galectin-3 may be a direct effect of this drug. Galectin-3 was higher in PVS compared with HVS and SVS, suggesting that the splanchnic region is a major site of galectin-3 synthesis. Low galectin-3 in HVS compared with PVS demonstrated hepatic removal.

CONCLUSIONS

Systemic galectin-3 is elevated in obesity and negatively correlates with glycated hemoglobin in T2D patients, pointing to a modifying function of galectin-3 in human metabolic diseases.

Promoter methylation in prostate cancer and its application for the early detection of prostate cancer using serum and urine samples

Prostate cancer is the second most common cancer and the second leading cause of cancer death in men. However, prostate cancer can be effectively treated and cured, if it is diagnosed in its early stages when the tumor is still confined to the prostate. Combined with the digital rectal examination, the PSA test has been widely used to detect prostate cancer. But, the PSA screening method for early detection of prostate cancer is not reliable due to the high prevalence of false positive and false negative results. Epigenetic alterations including hypermethylation of gene promoters are believed to be the early events in neoplastic progression and thus these methylated genes can serve as biomarkers for the detection of cancer from clinical specimens. This review discusses DNA methylation of several gene promoters during prostate carcinogenesis and evaluates the usefulness of monitoring methylated DNA sequences, such as GSTP1, RASSF1A, RARβ2 and galectin-3, for early detection of prostate cancer in tissue biopsies, serum and urine.

Inflammatory disease and cancer with a decrease in Kupffer cell numbers in Nucling-knockout mice

Nucling is a stress-inducible protein associated with apoptosomes. The cytochrome c-triggered formation of apoptosomes represents a key-initiating event in apoptosis. We have recently reported that Nucling regulates the apoptotic pathway by controlling the activation of NF-kappaB as well. Here we show that hepatocellular carcinoma (HCC) arising spontaneously against a background of hepatitis occurred more frequently in Nucling-knockout (KO) mice than wild-type (WT) mice. Biochemical serum testing revealed potential liver dysfunction with hypercholesterolemia in Nucling-KO males. In the background of Nucling-KO mice, we observed the up-regulation of TNFalpha, spontaneous NF-kappaB-activation and the induction of galectin-3 expression in liver. In addition, we observed a decrease in the number of Kupffer cells (KCs) in the KO mice. KCs are important for the hepatic immune system, acting as phagocytes or antigen-presenting cells (APCs). We found that KCs in Nucling-KO mice were apoptotic possibly through the up-regulation of TNFalpha. These observations indicate that Nucling is important for the regulation of NF-kappaB signals in liver. We propose that Nucling deficiency could be a powerful tool to reveal the NF-kappaB-related molecular networks leading to hepatitis and HCC development.

KSHV downregulation of galectin-3 in Kaposi's sarcoma

Galectins are a family of proteins that share an affinity for beta-galactoside containing glycoconjugates. In prostate, ovarian and breast cancer, downregulation of galectin-3 is associated with malignancy and tumor progression. Kaposi's sarcoma (KS) is characterized as an angioproliferative tumor of vascular endothelial cells and produces rare B cell lymphoproliferative diseases in the form of primary effusion lymphomas and some forms of multicentric Castleman's disease. Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiological agent of KS. We found reduced levels of galectin-3 expression in a significant fraction of latency-associated nuclear antigen (LANA)-positive spindle cell regions in human archival KS tissue and as measured in KS tissue microarrays. Here we demonstrate that galectin-3 protein expression is downregulated 10-fold in 10-day KSHV-infected dermal microvascular endothelial cells (DMVEC) accompanied by downregulation of message. There is loss of galectin-3 staining in KSHV-infected DMVEC by dual labeled immunohistochemistry in LANA-positive spindle cells. We observed a consistent downregulation of galectin-3 by time-course transcriptional analysis. Of the galectins assayed, only galectin-1 was also downregulated in KSHV-infected DMVEC. We examined 86 KS tumors; 19 were LANA positive (22%) and 67 LANA negative (78%). All 86 tumors were found to be galectin-3 positive; 11 of 19 showed reduced expression of galectin-3 in LANA-positive spindle cell regions. Our data suggest that KSHV vFLIP and LANA are the viral genes targeting galectin-3 downregulation. The contribution of host factors to the pathogenesis of KS is essential for early detection and development of innovative therapies for treatment.

Galectin-3: a novel mediator of heart failure development and progression

Galectins are a family of soluble beta-galactoside-binding lectins that play many important regulatory roles in inflammation, immunity, and cancer. Recently, a role for galectin-3 in the pathophysiology of heart failure (HF) has been suggested. Numerous studies have demonstrated the up-regulation of galectin-3 in hypertrophied hearts, its stimulatory effect on macrophage migration, fibroblast proliferation, and the development of fibrosis. The latter observation is particularly relevant as cardiac remodelling is an important determinant of the clinical outcome of HF and is linked to disease progression and poor prognosis. Because galectin-3 expression is maximal at peak fibrosis and virtually absent after recovery, routine measurement in patients with HF may prove valuable to identify those patients at highest risk for readmission or death, thus enabling physicians to tailor the level of care to individual patient needs. This review summarizes the most recent advances in galectin-3 research, with an emphasis on the role galectin-3 plays in the development and progression of HF.