Regulation of cancer-related gene expression by galectin-3 and the molecular mechanism of its nuclear import pathway

Study of immunosenescence in the occurrence and immunotherapy of gastrointestinal malignancies

In human beings heterogenous, pervasive and lethal malignancies of different parts of the gastrointestinal (GI) tract viz., tumours of the oesophagus, stomach, small intestine, colon, and rectum, represent gastrointestinal malignancies. Primary treatment modality for gastric cancer includes chemotherapy, surgical interventions, radiotherapy, monoclonal antibodies and inhibitors of angiogenesis. However, there is a need to improve upon the existing treatment modality due to associated adverse events and the development of resistance towards treatment. Additionally, age has been found to contribute to increasing the incidence of tumours due to immunosenescence-associated immunosuppression. Immunosenescence is the natural process of ageing, wherein immune cells as well as organs begin to deteriorate resulting in a dysfunctional or malfunctioning immune system. Accretion of senescent cells in immunosenescence results in the creation of a persistent inflammatory environment or inflammaging, marked with elevated expression of pro-inflammatory and immunosuppressive cytokines and chemokines. Perturbation in the T-cell pools and persistent stimulation by the antigens facilitate premature senility of the immune cells, and senile immune cells exacerbate inflammaging conditions and the inefficiency of the immune system to identify the tumour antigen. Collectively, these conditions contribute positively towards tumour generation, growth and eventually proliferation. Thus, activating the immune cells to distinguish the tumour cells from normal cells and invade them seems to be a logical strategy for the treatment of cancer. Consequently, various approaches to immunotherapy, viz., programmed death ligand-1 (PD-1) inhibitors, Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitors etc are being extensively evaluated for their efficiency in gastric cancer. In fact, PD-1 inhibitors have been sanctioned as late late-line therapy modality for gastric cancer. The present review will focus on deciphering the link between the immune system and gastric cancer, and the alterations in the immune system that incur during the development of gastrointestinal malignancies. Also, the mechanism of evasion by tumour cells and immune checkpoints involved along with different approaches of immunotherapy being evaluated in different clinical trials will be discussed.

BRAF mutation, selected miRNAs and genes expression in primary papillary thyroid carcinomas and local lymph node metastases

Mutations in cancer-related genes are now known to be accompanied by epigenetic events in carcinogenesis by modification of the regulatory pathways and expression of genes involved in the pathobiology. Such cancer-related mutations, miRNAs and gene expression may be promising molecular markers of the most common papillary thyroid carcinoma (PTC). However, there are limited data on their relationships. The aim of this study was to analyse the interactions between BRAF mutations, selected microRNAs (miR-21, miR-34a, miR-146b, and miR-9) and the expression of selected genes (LGALS3, NKX2-1, TACSTD2, TPO) involved in the pathogenesis of PTC. The study cohort included 60 primary papillary thyroid carcinomas (PTC) that were classified as classical (PTC/C; n=50) and invasive follicular variant (PTC/F; n=10), and 40 paired lymph node metastases (LNM). BRAF mutation status in primary and recurrent/persistent papillary thyroid carcinomas was determined. The mutation results were compared both between primary and metastatic cancer tissue, and between BRAF mutation status and selected genes and miRNA expression in primary PTC. Furthermore, miRNAs and gene expression were compared between primary PTCs and non-neoplastic tissue, and local lymph node metastatic tumor, respectively. All studied markers showed several significant mutual interactions and contexts. In conclusion, to the best our knowledge, this is the first integrated study of BRAF mutational status, the expression levels of mRNAs of selected genes and miRNAs in primary PTC, and paired LNM.

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.

Galectins as pivotal components in oncogenesis and immune exclusion in human malignancies

Galectins are galactoside-binding proteins, exerting numerous functions inside and outside the cell, particularly conferring adaptation to stress factors. For most of them, aberrant expression profiles have been reported in the context of cancer. Albeit not being oncogenic drivers, galectins can be harnessed to exacerbate the malignant phenotype. Their impact on disease establishment and progression is not limited to making cancer cells resistant to apoptosis, but is prominent in the context of the tumor microenvironment, where it fosters angiogenesis, immune escape and exclusion. This review focuses mainly on Gal-1, Gal-3 and Gal-9 for which the involvement in cancer biology is best known. It presents the types of galectin dysregulations, attempts to explain the mechanisms behind them and analyzes the different ways in which they favor tumour growth. In an era where tumour resistance to immunotherapy appears as a major challenge, we highlight the crucial immunosuppressive roles of galectins and the potential therapeutic benefits of combinatorial approaches including galectin inhibition.

Galectin-2 in Health and Diseases

Galectin-2 is a prototype member of the galactoside-binding galectin family. It is predominately expressed in the gastrointestinal tract but is also detected in several other tissues such as the placenta and in the cardiovascular system. Galectin-2 expression and secretion by epithelial cells has been reported to contribute to the strength of the mucus layer, protect the integrity of epithelia. A number of studies have also suggested the involvement of galectin-2 in tissue inflammation, immune response and cell apoptosis. Alteration of galectin-2 expression occurs in inflammatory bowel disease, coronary artery diseases, rheumatoid arthritis, cancer, and pregnancy disorders and has been shown to be involved in disease pathogenesis. This review discusses our current understanding of the role and actions of galectin-2 in regulation of these pathophysiological conditions.

Anti-Cancer Pectins and Their Role in Colorectal Cancer Treatment

A class of plant polysaccharides, pectin is known to display several medicinal properties including in cancer. There is some evidence that pectin from some fruits can reduce the severity of colorectal cancer (CRC) due to its antiproliferative, anti-inflammatory, antimetastatic and pro-apoptotic properties. Pectin fermentation in the colon induces antiproliferative activity via butyrate. Research also showed that pectin acts as a potent inducer of programmed cell death and cell-cycle arrest, thereby selectively targeting cancer cells. Pectin can limit oxidative stress to maintain cellular homeostasis while increasing reactive oxygen species damage to activate cancer cell death. Pectin regulates various signaling cascades, e.g., signal transduction and transcriptional activator and mitogen-activated protein kinase signaling, that contribute to its anticancer activity. By curbing inflammation-activated signaling and bolstering immune-protective mechanisms pectin can eradicate CRC. Due to its chemical structure, pectin can also inhibit galectin-3 and suppress tumor growth and metastasis. Prior reports also suggested that pectin is beneficial to use alongside the CRC standard care. Pectin can increase sensitivity to conventional CRC drugs, alleviate unwanted side effects and reduce drug resistance. Although some preclinical studies are promising, early clinical trials are showing some evidence for pectin's efficacy in tumor growth inhibition and preventing metastasis in some cancers; however, the clinical use of pectin in CRC therapy is not yet well established. Further studies are needed to confirm the efficacy of pectin treatment as a valid clinical therapy for CRC in humans.

Expression of Immune Checkpoints in Malignant Tumors: Therapy Targets and Biomarkers for the Gastric Cancer Prognosis

To increase the effectiveness of anticancer therapy based on immune checkpoint (IC) inhibition, some ICs are being investigated in addition to those used in clinic. We reviewed data on the relationship between PD-L1, B7-H3, B7-H4, IDO1, Galectin-3 and -9, CEACAM1, CD155, Siglec-15 and ADAM17 expression with cancer development in complex with the results of clinical trials on their inhibition. Increased expression of the most studied ICs—PD-L1, B7-H3, and B7-H4—is associated with poor survival; their inhibition is clinically significant. Expression of IDO1, CD155, and ADAM17 is also associated with poor survival, including gastric cancer (GC). The available data indicate that CD155 and ADAM17 are promising targets for immune therapy. However, the clinical trials of anti-IDO1 antibodies have been unsatisfactory. Expression of Galectin-3 and -9, CEACAM1 and Siglec-15 demonstrates a contradictory relationship with patient survival. The lack of satisfactory results of these IC inhibitor clinical trials additionally indicates the complex nature of their functioning. In conclusion, in many cases it is important to analyze the expression of other participants of the immune response besides target IC. The PD-L1, B7-H3, B7-H4, IDO1 and ADAM17 may be considered as candidates for prognosis markers for GC patient survival.

Pro64His (rs4644) Polymorphism Within Galectin-3 Is a Risk Factor of Differentiated Thyroid Carcinoma and Affects the Transcriptome of Thyrocytes Engineered via CRISPR/Cas9 System

Background: Galectin-3 (LGALS3) is an important glycoprotein involved in the malignant transformation of thyrocytes acting in the extracellular matrix, cytoplasm, and nucleus where it regulates TTF-1 and TCF4 transcription factors. Within LGALS3 gene, a common single-nucleotide polymorphism (SNP) (c.191C>A, p.Pro64His; rs4644) encoding for the variant Proline to Histidine at codon 64 has been extensively studied. However, data on rs4644 in the context of thyroid cancer are lacking. Thus, the aim of the present work was to evaluate the role of the rs4644 SNP as risk factor for differentiated thyroid cancer (DTC) and to determine the effect on the transcriptome in thyrocytes. Methods: A case/control association study in 1223 controls and 1142 unrelated consecutive DTC patients was carried out to evaluate the association between rs4644-P64H and the risk of DTC. We used the nonmalignant cell line Nthy-Ori (rs4644-C/A) and the CRISPR/Cas9 technique to generate isogenic cells carrying either the rs4644-A/A or rs4644-C/C homozygosis. Then, the transcriptome of the derivative and unmodified parental cells was analyzed by RNA-seq. Genes differentially expressed were validated by quantitative reverse transcription PCR and further tested in the parental Nthy-Ori cells after LGALS3 gene silencing, to investigate whether the expression of target genes was dependent on galectin-3 levels. Results: rs4644 AA genotype was associated with a reduced risk of DTC (compared with CC, OR_adj = 0.66; 95% confidence interval = 0.46-0.93; P_ass = 0.02). We found that rs4644 affects galectin-3 as a transcriptional coregulator. Among 34 genes affected by rs4644, HES1, HSPA6, SPC24, and NHS were of particular interest since their expression was rs4644-dependent (CC>AA for the first and AA>CC for the others), also in 574 thyroid tissues of Genotype-Tissue Expression (GTEx) biobank. Moreover, the expression of these genes was regulated by LGALS3-silencing. Using the proximity ligation assay in Nthy-Ori cells, we found that the TTF-1 interaction was genotype dependent. Conclusions: Our data show that in thyroid, rs4644 is a trans-expression quantitative trait locus that can modify the transcriptional expression of downstream genes, through the modulation of TTF-1.

Galectin-3 is modulated in pancreatic cancer cells under hypoxia and nutrient deprivation

Pancreatic ductal adenocarcinoma is one of the most aggressive tumors with a microenvironment marked by hypoxia and starvation. Galectin-3 has been evaluated in solid tumors and seems to present both pro/anti-tumor effects. So, this study aims to characterize the expression of Galectin-3 from pancreatic tumor cells and analyze its influence for cell survive and motility in mimetic microenvironment. For this, cell cycle and cell death were accessed through flow cytometry. Characterization of inside and outside Galectin-3 was performed through Real-Time Quantitative Reverse Transcription PCR (qRT-PCR), immunofluorescence, Western blot, and ELISA. Consequences of Galectin-3 extracellular inhibition were investigated using cell death and scratch assays. PANC-1 showed increased Galectin-3 mRNA expression when cultivated in hypoxia for 24 and 48 h. After 24 h in simultaneously hypoxic/deprived incubation, PANC-1 shows increased Galectin-3 protein and secreted levels. For Mia PaCa-2, cultivation in deprivation was determinant for the increasing in Galectin-3 mRNA expression. When cultivated in simultaneously hypoxic/deprived condition, Mia PaCa-2 also presented increasing for the Galectin-3 secreted levels. Treatment of PANC-1 cells with lactose increased the death rate when cells were incubated simultaneously hypoxic/deprived condition. Therefore, it is possible to conclude that the microenvironmental conditions modulate the Galectin-3 expression on the transcriptional and translational levels for pancreatic cancer cells.

Increased epithelial galectin-13 expression associates with eosinophilic airway inflammation in asthma

BACKGROUND

Airway eosinophilic inflammation is a central feature in asthma which is mainly driven by type 2 response. The expression of galectin-13 was up-regulated in a parasitic infection model which is also characterized by type 2 immune response. We hypothesized that galectin-13 may be involved in airway eosinophilic inflammation in asthma.

OBJECTIVE

To unveil the role of galectin-13 in asthma airway inflammation.

METHODS

We measured galectin-13 expressions in bronchial brushings, sputum, and plasma of asthma patients (n = 54) and healthy controls (n = 15), and analysed the correlations between galectin-13 expression and airway eosinophilia. We used human bronchial epithelial cell line 16HBE to investigate the possible mechanism by which galectin-13 participates in eosinophilic inflammation.

RESULTS

The expression of galectin-13 was markedly increased in subjects with asthma compared to controls. Epithelial galectin-13 mRNA levels in asthmatic subjects were strongly correlated with eosinophilic airway inflammation (the percentage of sputum eosinophils, the number of eosinophils in bronchial submucosa and FeNO) and the expression of Th2 signature genes (CLCA1, POSTN and SERPINB2). Inhaled corticosteroid (ICS) treatment reduced plasma galectin-13 levels, and baseline plasma galectin-13 levels reflect the response to ICS treatment. In cultured 16HBE cells, knockdown of galectin-13 suppressed IL-13-stimulated MCP-1 and eotaxin-1 expression by inhibiting the activation of EGFR and ERK.

CONCLUSIONS & CLINICAL RELEVANCE

Galectin-13 is a novel marker for airway eosinophilia in asthma, and may contribute to allergic airway eosinophilic inflammation by up-regulating the expression of MCP-1 and eotaxin-1. Plasma galectin-13 levels may be useful for predicting responses to ICS treatment.

Immunoexpression of galectin-3 and its potential relation to hypoxia-inducible factor-1α in ameloblastomas

In tumor biology, hypoxia triggers signaling pathways that induce transcription of genes related to angiogenesis, metastasis, glucose metabolism and apoptosis. We investigated the expression of hypoxia related proteins, galectin-3 (Gal-3) and hypoxia-inducible factor-1α (HIF-1α), in conventional (CA) and unicystic ameloblastomas (UA). We applied immunohistochemistry for Gal-3 and HIF-1α to 72 cases of ameloblastoma: 59 cases of CA and 13 cases of unicystic UA. Immunoexpression was evaluated semiquantitatively. Gal-3 expression was observed in 40% of the cases: 23/59 CA and 6/13 UA. HIF-1α immunostaining was observed in 55% of cases: 36/59 CA and 4/13 UA. 19 CA and 2 UA were positive for both markers. Immunostaining was evident in the center of the tumor islands, which exhibited squamous metaplasia or cystic degeneration. The expression of Gal-3 and HIF-1α in ameloblastomas could be interpreted as a response to hypoxic stress. Co-expression of both proteins in CA may suggest a potential interaction that participates in the biological behavior of this ameloblastoma variant.

Prognostic significance of galectin-3 expression in patients with resected NSCLC treated with platinum-based adjuvant chemotherapy

BACKGROUND

Galectin-3 (GAL3), a protein encoded by the LGALS3 gene, plays diverse roles in cancer initiation, progression, and drug resistance. Accordingly, high GAL3 expression in tumor cells is associated with poor prognosis in non-small cell lung cancer (NSCLC). However, the prognostic impact of GAL3 expression on patients with resected NSCLC receiving platinum-based adjuvant chemotherapy (AC) remains unclear. This study aimed to determine the prognostic significance of GAL3 expression in NSCLC patients receiving platinum-based AC.

METHODS

The study included 111 patients with completely resected stages II and IIIA NSCLC who were receiving platinum-based AC. GAL3 expression in cancer cells was evaluated immunohistochemically according to H-score ("histo score), with a score of ≥170 considered as high expression. The correlation of GAL3 expression with clinicopathological characteristics and survival was subsequently evaluated.

RESULTS

In survival analysis, GAL3 expression was significantly associated with recurrence-free survival (RFS) and overall survival (OS). In multivariate analysis, GAL3 expression was an independent predictive factor of RFS rather than OS.

CONCLUSIONS

GAL3 expression is a reliable biomarker to predict the prognosis of completely resected NSCLC patients receiving platinum-based AC.

Bridging the Gap of Drug Delivery in Colon Cancer: The Role of Chitosan and Pectin Based Nanocarriers System

Colon cancer is one of the most prevalent diseases, and traditional chemotherapy has not been proven beneficial in its treatment. It ranks second in terms of mortality due to all cancers for all ages. Lack of selectivity and poor biodistribution are the biggest challenges in developing potential therapeutic agents for the treatment of colon cancer. Nanoparticles hold enormous prospects as an effective drug delivery system. The delivery systems employing the use of polymers, such as chitosan and pectin as carrier molecules, ensure the maximum absorption of the drug, reduce unwanted side effects and also offer protection to the therapeutic agent from quick clearance or degradation, thus allowing an increased amount of the drug to reach the target tissue or cells. In this systematic review of published literature, the author aimed to assess the role of chitosan and pectin as polymer-carriers in colon targeted delivery of drugs in colon cancer therapy. This review summarizes the various studies employing the use of chitosan and pectin in colon targeted drug delivery systems.

Galectin-3 mediates high-glucose-induced cardiomyocyte injury by the NADPH oxidase/reactive oxygen species pathway

Galectin-3 is a member of the β-galactoside-binding lectin family taking part in the regulation of inflammation, angiogenesis, and fibrosis. This study was designed to study the improved effect of galectin-3 inhibition on diabetic cardiomyopathy (DCM). Sprague-Dawley rats were randomized into the control, DCM, and DCM + modified citrus pectin (MCP) (a galectin-3 pharmacological inhibitor) groups. After 8 weeks, streptozotocin-induced DCM led to high blood glucose level, oxidative stress, cardiac injury, and dysfunction accompanied by suppressed body mass. On the contrary, MCP (100 mg·kg^-1·day^-1) administration improved body mass and blood glucose level and attenuated cardiac injury and dysfunction in DCM rats. Additionally, MCP attenuated pathological changes in plasma and myocardial tissue markers of oxidative stress, such as hydrogen peroxide and malonyldialdehyde, although it did not change superoxide dismutase activities, which were decreased in the DCM group. The levels of oxidative stress associated proteins evaluated by Western blot, such as p67^phox and NADPH oxidase 4, were obviously increased in the DCM group, while they were reversed by MCP treatment. Therefore, galectin-3-mediated high-glucose-induced cardiomyocyte injury and galectin-3 inhibition attenuated DCM by suppressing NADPH oxidase. These findings suggested that galectin-3 could be a potential target for treatment of patients with DCM.

How galectins have become multifunctional proteins

Having identified glycans of cellular glycoconjugates as versatile molecular messages, their recognition by sugar receptors (lectins) is a fundamental mechanism within the flow of biological information. This type of molecular interplay is increasingly revealed to be involved in a wide range of (patho)physiological processes. To do so, it is a vital prerequisite that a lectin (and its expression) can develop more than a single skill, that is the general ability to bind glycans. By studying the example of vertebrate galectins as a model, a total of five relevant characteristics is disclosed: i) access to intra- and extracellular sites, ii) fine-tuned gene regulation (with evidence for co-regulation of counterreceptors) including the existence of variants due to alternative splicing or single nucleotide polymorphisms, iii) specificity to distinct glycans from the glycome with different molecular meaning, iv) binding capacity also to peptide motifs at different sites on the protein and v) diversity of modular architecture. They combine to endow these lectins with the capacity to serve as multi-purpose tools. Underscoring the arising broad-scale significance of tissue lectins, their numbers in terms of known families and group members have steadily grown by respective research that therefore unveiled a well-stocked toolbox. The generation of a network of (ga)lectins by evolutionary diversification affords the opportunity for additive/synergistic or antagonistic interplay in situ, an emerging aspect of (ga)lectin functionality. It warrants close scrutiny. The realization of the enormous potential of combinatorial permutations using the five listed features gives further efforts to understand the rules of functional glycomics/lectinomics a clear direction.

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.

Predictive importance of galectin-3 for recurrence of non-small cell lung cancer

OBJECTIVE

The predictive importance of galectin-3 in non-small cell lung cancer (NSCLC) has not been elucidated. We examined whether galectin-3 could serve as a predictor for tumor recurrence in NSCLC.

METHODS

In 42 consecutive patients with NSCLC who underwent radical resection, galectin-3 expression in tumor cells was examined by immunohistochemistry. Galectin-3 levels in serum were assessed before surgery and 1 month after surgery by enzyme-linked immunosorbent assays.

RESULTS

Higher expression of galectin-3 in tumor cells was associated significantly with lymphatic invasion (p = 0.049) and tumor recurrence (p = 0.001). The Kaplan-Meier curves for relapse-free survival after radical resection showed that patients with high expression of galectin-3 had significantly shorter relapse-free survival than those with low expression of galectin-3 (p < 0.001). The serum level of galectin-3 was not reduced after radical resection, and there was no significant correlation between the serum level of galectin-3 and recurrence.

CONCLUSIONS

Galectin-3 expression in tumor cells could serve as a predictive factor for recurrence, but serum level of galectin-3 is not useful for predicting NSCLC recurrence.

Design-functionality relationships for adhesion/growth-regulatory galectins

Glycan-lectin recognition is assumed to elicit its broad range of (patho)physiological functions via a combination of specific contact formation with generation of complexes of distinct signal-triggering topology on biomembranes. Faced with the challenge to understand why evolution has led to three particular modes of modular architecture for adhesion/growth-regulatory galectins in vertebrates, here we introduce protein engineering to enable design switches. The impact of changes is measured in assays on cell growth and on bridging fully synthetic nanovesicles (glycodendrimersomes) with a chemically programmable surface. Using the example of homodimeric galectin-1 and monomeric galectin-3, the mutual design conversion caused qualitative differences, i.e., from bridging effector to antagonist/from antagonist to growth inhibitor and vice versa. In addition to attaining proof-of-principle evidence for the hypothesis that chimera-type galectin-3 design makes functional antagonism possible, we underscore the value of versatile surface programming with a derivative of the pan-galectin ligand lactose. Aggregation assays with N,N'-diacetyllactosamine establishing a parasite-like surface signature revealed marked selectivity among the family of galectins and bridging potency of homodimers. These findings provide fundamental insights into design-functionality relationships of galectins. Moreover, our strategy generates the tools to identify biofunctional lattice formation on biomembranes and galectin-reagents with therapeutic potential.

Galectin-3 Inhibits Cancer Metastasis by Negatively Regulating Integrin β3 Expression

Galectin-3 (Gal-3; gene LGALS3) is a member of the β-galactose-binding lectin family. Previous studies showed that Gal-3 is expressed in several tissues across species and functions as a regulator of cell proliferation, apoptosis, adhesion, and migration, thus affecting many aspects of events, such as angiogenesis and tumorigenesis. Although several reports have suggested that the level of Gal-3 expression correlates positively with tumor progression, herein we show that highly metastatic mouse melanoma B16/BL6 cells express less Gal-3 than B16 cells with a lower metastatic potential. It was found that overexpression of Gal-3 in melanoma cells in fact suppresses metastasis. In contrast, knocking out Gal-3 expression in cancer cells promoted cell aggregation mediated through interactions with platelets and fibrinogen in vitro and increased the number of metastatic foci in vivo. Thus, reduced Gal-3 expression results in the up-regulation of β3 integrin expression, and this contributes to metastatic potential. These findings indicate that changes of Gal-3 expression in cancer cells during tumor progression influence the characteristics of metastatic cells.

Primordial odontogenic tumor: An immunohistochemical profile

BACKGROUND

Primordial Odontogenic Tumor (POT) is a recently described odontogenic tumor characterized by a variably cellular loose fibrous tissue with areas similar to the dental papilla, covered by cuboidal to columnar epithelium that resembles the internal epithelium of the enamel organ, surrounded at least partly by a delicate fibrous capsule. The purpose of this study was to investigate the possible histogenesis and biological behavior of this rare tumor by means of a wide immunohistochemical analysis of its epithelial and mesenchymal components.

MATERIAL AND METHODS

The immunoexpression of twenty-three different antibodies were evaluated in four cases of POT.

RESULTS

The epithelial cells that cover the periphery of the tumor showed immunopositivity for Cytokeratins 14 and 19, while Amelogenin, Glut-1, MOC-31, Caveolin-1. Galectin-3, PITX2, p53, Bax, Bcl-2, Survivin and PTEN were variably expressed in focal areas. The mesenchymal component of the tumor was positive for Vimentin, Syndecan-1, PITX2, Endoglin (CD105), CD 34, Cyclin D1, Bax, Bcl-2, Survivin and p53. PTEN and CD 90 showed a moderate positivity. BRAF V600E and Calretinin were negative in all samples. Cell proliferation markers (Ki-67, MCM-7) were expressed in <5% of the tumor cells.

CONCLUSIONS

According to these immunohistochemical findings, we may conclude that POT is a benign odontogenic tumor in which there is both epithelial and mesenchymal activity during its histogenesis, as there is expression of certain components in particular zones in both tissues that suggests this tumor develops during the immature (primordial) stage of tooth development, leading to its inclusion within the group of benign mixed epithelial and mesenchymal odontogenic tumours in the current World Health Organization classification of these lesions.

Tumor cells interact with red blood cells via galectin-4 - a short report

BACKGROUND

The ability of tumor cells to invade and metastasize is relevant to the process of cancer progression and, as such, it represents an obstacle to cancer cure. So far, limited information is available on interactions between circulating tumor cells and blood cells. It is well-documented that galectin-4 is upregulated in many types of tumor cells and is involved in metastasis. Here, we address the hypothesis that tumor cells may interact with red blood cells (RBCs) via galectin-4.

METHODS

High galectin-4 expressing colon, normal pancreatic and pancreatic cancer-derived cell lines (n = 5) were incubated with peripheral blood cells from different donors. Their interactions and associated proteins were examined by immunostaining and live cell imaging.

RESULTS

We found that (endogenous or exogenous) galectin-4 expressing tumor cells interact directly with RBCs. We also observed an accumulation of galectin-4 and human blood group antigens at the contact sites between these cells. By comparing the number of RBCs attaching to each tumor cell, we found that cells with high pre-incubation expression levels of galectin-4 attached significantly more RBCs than those with low expression levels (p < 1 × 10^-7). Conversely, we found that RBC attachment induces galectin-4 expression in tumor cells.

CONCLUSIONS

From our data we conclude that tumor cells directly interact with red blood cells via galectin-4.

Expression levels of β-catenin and galectin-3 in meningioma and their effect on brain invasion and recurrence: a tissue microarray study

Objective:

Meningiomas are neoplasms that arise from the meninges of the central nervous system (CNS). They constitute about 25.6% of CNS tumors diagnosed in Egypt. Some morphological variants of meningiomas display aggressive behavior, leading to brain-invasive growth pattern. Although meningiomas are usually treated by complete surgical excision, the risk of postoperative recurrence remains. Hence, additional biomarkers for predicting aggressive behavior must be discovered. This study aims to explore the clinical and biological relevance of the protein expression levels of β-catenin and galectine-3 in meningioma and to understand the pathobiology of this neoplasm.

Methods:

This retrospective study was carried out on 153 cases of meningioma by using tissue microarrays and immunohistochemistry for β-catenin and galectine-3.

Results:

High β-catenin expression was significantly associated with transitional and meningiotheliomatous meningiomas, low tumor grade, low recurrence rate, and low incidence of brain invasion. Meanwhile, high galectin-3 expression was associated with brain invasion, recurrence, high tumor grade, and tumor type. Logistic regression analysis indicated that among all variables included in the model, β-catenin and galactin-3 expression levels were significant predictors of tumor recurrence (P<0.001).

Conclusions:

Galectin-3 and β-catenin are involved in meningioma recurrencebut not in brain invasion. These molecules could be important potential therapeutic targets and predictors for meningiomas.

Quercetin Confers Tumoricidal Activity Through Multipathway Mechanisms in A N-Methylnitrosourea Rat Model of Colon Cancer

Objective: This research was conducted to explore mechanisms behind the potency of quercetin in inhibiting colon cancer induced in an experimental model. Materials and Methods: Forty adult male rats of Wistar strain were distributed into 4 groups; a negative control group, a colon cancer bearing group, a quercetin-treated group and a 5-fluorouracil (5-FU)-treated group. Serum TAG72 and GAL3 levels were quantified by ELISA. Colonic Wnt5a and Axin-1 gene expression was estimated by PCR. In addition, colonic tissues were subjected to immunohistochemical examination of Bax expression and histological investigation of histopathological alterations. Results: Quercetin elicited significant reduction in serum TAG72 and GAL3 levels, in addition to significant suppression of colonic Wnt5a gene expression and amplification of colonic Axin-1 gene expression. Also, it caused moderate positive reaction for Bax in mucosal epithelium. Conclusion: The present research provides experimental evidence about the activity of quercetin in the colon cancer of rats. Inhibitory effects on cancer development might be ascribable to regulatory action on Wnt signaling and induction of apoptosis.

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-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.

Hypoxia Up-Regulates Galectin-3 in Mammary Tumor Progression and Metastasis

The tumor microenvironment encompasses several stressful conditions for cancer cells such as hypoxia, oxidative stress and pH alterations. Galectin-3, a well-studied member of the beta-galactoside-binding animal family of lectins has been implicated in multiple steps of metastasis as cell-cell and cell-ECM adhesion, promotion of angiogenesis, cell proliferation and resistance to apoptosis. However, both its aberrantly up- and down-regulated expression was observed in several types of cancer. Thus, the mechanisms that regulate galectin-3 expression in neoplastic settings are not clear. In order to demonstrate the putative role of hypoxia in regulating galectin-3 expression in canine mammary tumors (CMT), in vitro and in vivo studies were performed. In malignant CMT cells, hypoxia was observed to induce expression of galectin-3, a phenomenon that was almost completely prevented by catalase treatment of CMT-U27 cells. Increased galectin-3 expression was confirmed at the mRNA level. Under hypoxic conditions the expression of galectin-3 shifts from a predominant nuclear location to cytoplasmic and membrane expressions. In in vivo studies, galectin-3 was overexpressed in hypoxic areas of primary tumors and well-established metastases. Tumor hypoxia thus up-regulates the expression of galectin-3, which may in turn increase tumor aggressiveness.

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.

Expression of galectin-3 in gastric adenocarcinoma

BACKGROUND & OBJECTIVES

Galectin-3 a member of the galectin family is an endogenous β-galactoside binding lectin. It has been found to be associated with cell adhesion, recognition, proliferation, differentiation, immunomodulation, angiogenesis, apoptosis and can be a reliable marker for cancer aggressiveness. The aim of this study was to verify protein expression in gastric adenocarcinoma tissues and correlate the results with the clinical aspects in the study population.

METHODS

Galectin-3 expression was examined by immunohistochemistry in 57 samples of gastric adenocarcinomas tissues. Galectin-3 protein expression was observed in the cytoplasm and the nucleus of examined tissues.

RESULTS

Thirty one (54.4%) samples had strong or moderate staining and 26 (45.6%) tumours had negative or weak staining. The galectin-3 did not show association with the sex (p=0.347), age (p=0.999), Lauren's classification (p=0.731) and TNM stage (p=0.222). Regarding the TNM stage, 66.7 per cent of stage I tumours had strong or moderate staining; with tumours stage IV this percentage was 33.3 per cent.

INTERPRETATION & CONCLUSION

Our results suggest that gal-3 is not a reliable biomarker for prognosis of the gastric adenocarcinoma by immunohistochemistry. Further studies need to be done on a large sample of tumour tissues in different clinical staging.

Alternations of galectin levels after renal transplantation

OBJECTIVES

Galectins (gals), a growing family of β-galactoside-binding animal lectins, have been implicated in a variety of biological processes including fibrosis, angiogenesis, and immune activation, all of which are involved in hemodialysis (HD) and renal transplantation (RTx). In this study, we aimed to investigate serum gal levels in HD and RTx recipients.

DESIGN AND METHODS

41 normal subjects, 41 RTx recipients and 32 HD patients were recruited for this study. RTx recipients were evaluated before transplantation as well as 3 months afterwards. Serum gals-1, 2, 3, 4, 8, and 9 were measured both at baseline and 3 months later in each group.

RESULTS

At baseline, there were no differences in gals-1, 2, 3, 4, 8, and 9 between the RTx and HD groups. However, the levels of gals-1, 2, 3, 8, and 9 in the RTx and HD groups were higher than that of normal subjects. In paired analyses, gals-1, 2, and 3 were significantly decreased in RTx patients (P<0.0001) at 3 months, while there was no change in the HD group. However, levels of gals-4, 8, and 9 did not significantly change in either the HD or RTx group.

CONCLUSION

Gal-1, 2, and 3 levels were high in maintenance HD patients. Kidney transplantation improved gal-1, 2, and 3 levels.

Ablation of galectin-3 induces p27(KIP1)-dependent premature senescence without oncogenic stress

Premature senescence induced by oncogenic stimuli or tumor suppressor activation plays opposing roles in tumorigenesis. Here, we propose that galectin-3, a β-galactoside-binding lectin, regulates premature senescence without oncogenic stress. We detected premature senescence, decreased Skp2, and increased p27^KIP1 expression in galectin-3 knockout MEFs and galectin-3-depleted gastric cancer cells. Interestingly, galectin-3 depletion did not affect other senescence inducers such as p14^ARF, p16^INK4A, and p21^WAF1/CIP1, suggesting that galectin-3-regulated senescence is p27^KIP1 dependent. We demonstrate that galectin-3 depletion decreases retinoblastoma protein (Rb) phosphorylation (Ser780, Ser807/811), cyclin D1 and CDK4 expression, and E2F1 transcriptional activation. Galectin-3 directly interacts with the cyclin D1/CDK4 complex and promotes hyperphosphorylation of Rb. It also blocks the inhibition of E2F1 transcription, thereby increasing the expression of Skp2 and reducing the stability of p27^KIP1 to promote the proliferation of gastric cancer cells. Xenograft mice with galectin-3-depleted gastric cancer cells display tumor growth retardation that is reversed by Skp2 overexpression. Increased expression of galectin-3 is also associated with the advanced TNM (tumor, lymph node, metastasis) system, clinicopathological stage, and lymph node metastases. The probability of survival was significantly decreased in gastric cancer patients with galectin-3^high p27^KIP1-lowcells. Taken together, our results show that galectin-3 may accelerate gastric tumorigenesis by inhibiting premature senescence.

Vascular endothelial growth factor C enhances cervical cancer cell invasiveness via upregulation of galectin-3 protein

Vascular endothelial growth factor C (VEGF-C) promotes cervical cancer metastasis, while the detailed mechanism remains obscure. Recent evidence shows that galectin-3 (Gal-3), a glycan binding protein, interacts with the VEGF receptors and reinforces their signal transduction. In this study, we investigated the role of Gal-3 in VEGF-C-induced cervical cancer cell invasion. On cervical carcinoma cell line SiHa cells, silencing of Gal-3 expression with specific siRNA largely impaired VEGF-C-enhanced cell invasion. Treatment with VEGF-C for 12-48 h enhanced Gal-3 protein expression, which was inhibited by the addition of NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC). Moreover, the silencing of NF-κB subunit p65 expression with specific siRNA attenuated VEGF-C-enhanced Gal-3 expression, suggesting that NF-κB is the key intermediate. Under VEGF-C stimulation, an enhanced interaction between VEGF receptor-3 (VEGF-R3) and Gal-3 was found, which may possibly lead to VEGF-R3 activation since exogenous Gal-3 induced VEGF-R3 phosphorylation in a dose- and time-dependent manner. In conclusion, our findings implied that VEGF-C enhanced cervical cancer invasiveness via upregulation of Gal-3 protein through NF-κB pathway, which may shed light on potential therapeutic strategies for cervical cancer therapy.

Galectin-4, a novel predictor for lymph node metastasis in lung adenocarcinoma

Metastasis is still a major issue in cancer, and the discovery of biomarkers predicting metastatic capacity is essential for the development of better therapeutic strategies for treating lung adenocarcinoma. By using a proteomic approach, we aimed to identify novel predictors for lymph node metastasis in lung adenocarcinoma. Two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis showed 6 spots differentially expressed between lymph node metastasis-positive and lymph node metastasis-negative groups in a discovery set. Subsequent mass spectrometry showed that 2 of these spots were derived from galectin-4, and western blot analysis confirmed the overexpression of galectin-4 in metastatic samples. The predictive value of galectin-4 was confirmed by immunohistochemical analysis for a validation set consisting of 707 surgically resected specimens of lung adenocarcinomas (stages I to IV). We observed that 148 lung adenocarcinomas (20.9%) expressed galectin-4, which was significantly associated with variables of disease progression such as tumor size (p<0.0001), pleural invasion (p = 0.0071), venous invasion (p = 0.0178), nodal status (p = 0.0007), and TNM stage (p<0.0001). By the multivariate analysis, Galectin-4 expression was revealed as one of the independent predictor for lymph node metastasis, together with solid predominant and micropapillary histologic pattern. Furthermore, galectin-4 expression was revealed to be an independent predictor for lymph node metastasis and an adverse survival factor in patients with lung adenocarcinoma of acinar predominant type. Galectin-4 plays an important role in metastatic process of lung adenocarcinoma. Immunohistochemical testing for galectin-4 expression may be useful together with the detection of specific histology to predict the metastatic potential of lung adenocarcinoma.

Galectin-3 silencing inhibits epirubicin-induced ATP binding cassette transporters and activates the mitochondrial apoptosis pathway via β-catenin/GSK-3β modulation in colorectal carcinoma

Multidrug resistance (MDR), an unfavorable factor compromising the treatment efficacy of anticancer drugs, involves the upregulation of ATP binding cassette (ABC) transporters and induction of galectin-3 signaling. Galectin-3 plays an anti-apoptotic role in many cancer cells and regulates various pathways to activate MDR. Thus, the inhibition of galectin-3 has the potential to enhance the efficacy of the anticancer drug epirubicin. In this study, we examined the effects and mechanisms of silencing galectin-3 via RNA interference (RNAi) on the β-catenin/GSK-3β pathway in human colon adenocarcinoma Caco-2 cells. Galectin-3 knockdown increased the intracellular accumulation of epirubicin in Caco-2 cells; suppressed the mRNA expression of galectin-3, β-catenin, cyclin D1, c-myc, P-glycoprotein (P-gp), MDR-associated protein (MRP) 1, and MRP2; and downregulated the protein expression of P-gp, cyclin D1, galectin-3, β-catenin, c-Myc, and Bcl-2. Moreover, galectin-3 RNAi treatment significantly increased the mRNA level of GSK-3β, Bax, caspase-3, and caspase-9; remarkably increased the Bax-to-Bcl-2 ratio; and upregulated the GSK-3β and Bax protein expressions. Apoptosis was induced by galectin-3 RNAi and/or epirubicin as demonstrated by chromatin condensation, a higher sub-G1 phase proportion, and increased caspase-3 and caspase-9 activity, indicating an intrinsic/mitochondrial apoptosis pathway. Epirubicin-mediated resistance was effectively inhibited via galectin-3 RNAi treatment. However, these phenomena could be rescued after galectin-3 overexpression. We show for the first time that the silencing of galectin-3 sensitizes MDR cells to epirubicin by inhibiting ABC transporters and activating the mitochondrial pathway of apoptosis through modulation of the β-catenin/GSK-3β pathway in human colon cancer cells.

Design and synthesis of glycoprotein-based multivalent glyco-ligands for influenza hemagglutinin and human galectin-3

We report a facile synthesis of glycoprotein-based glyco-ligands and their binding with influenza hemagglutinin and human galectin-3. Human serum albumin (HSA) was used as the scaffold and an Asn-linked complex type N-glycan prepared from chicken eggs was used as the glycan building block. It was found that Cu(I)-catalyzed alkyne-azide cycloaddition reaction (click chemistry) between the alkyne-labeled glycan and the azide-tagged HSA led to an efficient formation of the glycoconjugates. The density of glycan ligands on the protein scaffold was readily varied by changing the molar ratios of the two reactants. Binding studies indicated that the sialylated and desialylated multivalent glycoligands could selectively bind to influenza hemagglutinin and human galectin-3, respectively, with high affinity. In the two glycan-lectin interactions, a clear multivalent effect was observed. Moreover, a cell-based assay showed that the synthetic multivalent glyco-ligands could efficiently inhibit the attachment of galectin-3 to human prostate cancer and lung cancer cell lines. This study suggests that the synthetic glycoprotein-based glyco-ligands can be useful for different applications, including blocking the function of galectin-3 in cancer metastasis.

Colon-specific delivery of 5-fluorouracil from zinc pectinate pellets through in situ intracapsular ethylcellulose-pectin plug formation

Conventional fluid-bed and immersion film coating of hydrophilic zinc pectinate pellets by hydrophobic ethylcellulose is met with fast drug release. This study explored in situ intracapsular pellet coating for colon-specific delivery of 5-fluorouracil (5-FU). The solid coating powder constituted ethylcellulose and pectin in weight ratios of 11:0 to 2:9. Its weight ratio to pellets varied between 2:3 and 3:2. Pectin was used as excipient of core pellets and coating powder in view of its potential use in colon cancer treatment. Delayed 5-FU release and core pectin dissolution were attainable when the weight ratio of solid coating powder to pellets was kept at 3:2, and weight ratio of ethylcellulose and pectin in coating powder was kept at 8:3 with particle size of ethylcellulose reduced to 22 μm. In situ intracapsular wetting of pectin coat by dissolution medium resulted in the formation of ethylcellulose plug interconnecting with pellets through the binding action of pectin. Less than 25% of drug was released at the upper gastrointestinal tract. The majority of drug was released upon prolonged dissolution and in response to colonic enzyme pectinase, which digested core pellets.

Galectin labeling of cells from paraffinized tissues may serve as a diagnostic tool in the detection and classification of thyroid carcinomas

This study seeks to determine whether the relative levels of attachment to galectins 1 and 3 of cells from thyroid tissues embedded in paraffin blocks can differentiate thyroid tumors from normal tissues. A total of 48 thyroid paraffin sample blocks from 4 groups of patients were analyzed: 12 samples served as controls, 12 samples were from patients with thyroid adenoma, 12 samples were from patients with thyroid follicular carcinoma, and 12 samples were from patients with thyroid papillary carcinoma. The relative attachment of cells to galectins 1 and 3 antigens was determined using the InnoCyte™ ECM Cell Adhesion kit at different cell sample concentrations. All of the samples from thyroid tissue preparations showed attachment to galectins 1 and 3. The samples from tissues with a diagnosis of adenoma, follicular and papillary carcinoma showed an increased adherence to galectins 1 and 3 relative to the controls. Significant differences were found between the means of the adherent cells from the adenomas compared with the follicular and papillary carcinoma samples. When the outcomes from the galectins 1 and 3 cell surface binding were compared, no statistical differences were found. The cells from adenoma and carcinoma samples show more adhesion to galectins 1 and 3 than cells from the control samples. The samples prepared from follicular and papillary carcinomas show more cells adherent to galectins 1 and 3 than those from the adenomas.

Galectin-3 expression in response to LPS, immunomodulatory drugs and exogenously added galectin-3 in monocyte-like THP-1 cells

Galectin-3, a structurally unique beta-galactoside-binding lectin, through the specific protein-protein and protein-carbohydrate interactions participates in numerous biological processes, such as cell proliferation and apoptosis, adhesion and activation. Its expression and secretion by until now an unknown mechanism are modulated by diverse molecules and are dependent on different physiological and pathophysiological conditions. By autocrine and paracrine actions, galectin-3 modulates many immune reactions and affects various immune cells, particularly those of monocyte-macrophage lineage. This is why galectin-3 has recently become an attractive therapeutic target. However, molecular mechanisms of its actions as well as regulatory mechanism of its expression and activation are still largely unknown. In this study, we show that lipopolysaccharide (LPS) provokes upregulation of galectin-3 expression on both gene and protein level in monocyte-like THP-1 cells, which can be inhibited by dexamethasone, but not with non-steroidal anti-inflammatory drugs aspirin and indomethacin. Resting and LPS-challenged monocyte-like THP-1 cells do not have detectable amount of surface-bound galectin-3, but are able to bind exogenously added galectin-3 with the same capacity. Although galectin-3 is generally considered to be a pro-inflammatory molecule, here we show that the exogenously added galectin-3 does not affect interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-12p70 and TNF-α production in resting and LPS-activated monocyte-like THP-1 cells nor influences its own gene expression level in those cells.

Synergistic and additive effects of modified citrus pectin with two polybotanical compounds, in the suppression of invasive behavior of human breast and prostate cancer cells

AIM

The objective of this study was to evaluate the combined effect of a known galectin-3 inhibitor, PectaSol-C modified citrus pectin (MCP), and 2 novel integrative polybotanical compounds for breast and prostate health, BreastDefend (BD) and ProstaCaid (PC), on invasive behavior in human breast and prostate cancer cells in vitro, respectively.

METHODS

The effect of MCP and BD and of MCP and PC on invasiveness was assessed by cell adhesion, cell migration, and cell invasion assays. Secretion of urokinase plasminogen activator (uPA) was determined by Western blot analysis.

RESULTS

Although low concentrations of MCP (0.25-1.0 mg/mL) do not suppress cell adhesion of breast or prostate cancer cells, the combination of MCP with BD or PC synergistically inhibits adhesion of these cells. Dose-dependent inhibition of breast and prostate cancer cell migration by MCP (0.25-1.0 mg/mL) is synergistically enhanced by BD (20 µg/mL) and PC (10 µg/mL), respectively. BD or PC did not further inhibit the invasion of breast and prostate cancer cells by MCP; however, the combination of MCP with BD or PC suppressed secretion of uPA from breast and prostate cancer cells, respectively.

CONCLUSION

The combination of MCP with BD and of MCP with PC synergistically inhibits the metastatic phenotypes of human breast and prostate cancer cells, respectively. Further studies confirming these observations in animal models of breast and prostate cancer metastasis are warranted.

Galectins in acute and chronic inflammation

Galectins are animal lectins that bind to β-galactosides, such as lactose and N-acetyllactosamine, in free form or contained in glycoproteins or glycolipids. They are located intracellularly or extracellularly. In the latter they exhibit bivalent or multivalent interactions with glycans on cell surfaces and induce various cellular responses, including production of cytokines and other inflammatory mediators, cell adhesion, migration, and apoptosis. Furthermore, they can form lattices with membrane glycoprotein receptors and modulate receptor properties. Intracellular galectins can participate in signaling pathways and alter biological responses, including apoptosis, cell differentiation, and cell motility. Current evidence indicates that galectins play important roles in acute and chronic inflammatory responses, as well as other diverse pathological processes. Galectin involvement in some processes in vivo has been discovered, or confirmed, through studies of genetically engineered mouse strains, each deficient in a given galectin. Current evidence also suggests that galectins may be therapeutic targets or employed as therapeutic agents for these inflammatory responses.

Galectin-3 and the skin

Galectin-3 is highly expressed in epithelial cells including keratinocytes and is involved in the pathogenesis of inflammatory skin diseases by affecting the functions of immune cells. For example, galectin-3 can contribute to atopic dermatitis (AD) by promoting polarization toward a Th2 immune response by regulating dendritic cell (DC) and T cell functions. In addition, galectin-3 may be involved in the development of contact hypersensitivity by regulating the migratory capacity of antigen presenting cells. Galectin-3 may act as a regulator of epithelial tumor progression and development through various signaling pathways, such as inhibiting keratinocyte apoptosis through regulation of the activation status of extracellular signal-regulated kinase (ERK) and activated protein kinase B (AKT). Galectin-3 is detected at different stages of melanoma development. In contrast, a marked decrease in the expression of galectin-3 is observed in non-melanoma skin cancers, such as squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). Galectin-3 may play an important role in tumor cell growth, apoptosis, cell motility, invasion, and metastasis. Galectin-3 may be a novel therapeutic target for a variety of skin diseases.

Serum galectin-2, -4, and -8 are greatly increased in colon and breast cancer patients and promote cancer cell adhesion to blood vascular endothelium

PURPOSE

Adhesion of disseminating tumor cells to the blood vascular endothelium is a pivotal step in metastasis. Previous investigations have shown that galectin-3 concentrations are increased in the bloodstream of patients with cancer and that galectin-3 promotes adhesion of disseminating tumor cells to vascular endothelium in vitro and experimental metastasis in vivo. This study determined the levels of galectin-1, -2, -3, -4, -8, and -9 in the sera of healthy people and patients with colon and breast cancer and assessed the influence of these galectins on cancer-endothelium adhesion.

EXPERIMENTAL DESIGN

Serum galectins and auto-anti-MUC1 antibodies were assessed using ELISA and mucin protein (MUC1) glycan microarrays, and cancer-endothelium adhesion was determined using monolayers of human microvascular lung endothelial cells.

RESULTS

The levels of serum galectin-2, -3, -4, and -8 were significantly increased up to 31-fold in patients with cancer and, in particular, those with metastases. As previously shown for galectin-3, the presence of these galectins enhances cancer-endothelium adhesion by interaction with the Thomsen-Friedenreich (TF; Galβ1,3GalNAcα-) disaccharide on cancer-associated MUC1. This causes MUC1 cell surface polarization, thus exposing underlying adhesion molecules that promote cancer-endothelium adhesion. Elevated circulating galectin-2 levels were associated with increased mortality in patients with colorectal cancer, but this association was suppressed when anti-MUC1 antibodies with specificity for the TF epitope of MUC1 were also present in the circulation.

CONCLUSIONS

Increased circulation of several members of the galectin family is common in patients with cancer and these may, like circulating galectin-3, also be involved in metastasis promotion.