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galectin-1 and galectin-3 expression in human bladder transitional-cell carcinomas.

Galectin-1 and galectin-3 are galactoside-binding proteins involved in different steps of tumor progression and potential targets for therapy. We have investigated the expression of these galectins in 38 human bladder transitional-cell carcinomas of different histological grade and clinical stage and in 5 normal urothelium samples. Galectin-1 mRNA levels were highly increased in most high-grade tumors compared with normal bladder or low-grade tumors. Western blot and immuno-histochemical analysis of normal and neoplastic tissues revealed a higher content of galectin-1 in tumors. Galectin-3 mRNA levels were also increased in most tumors compared with normal urothelium, but levels were comparable among tumors of different histological grade.

Adult↗

Expression of galectins in head and neck squamous cell carcinoma.

BACKGROUND: Galectins are carbohydrate-binding proteins thought to be important for cell growth and differentiation, whose expression is altered in some tumors with aggressive phenotype. Our objective was to evaluate the expression of galectins in head and neck squamous cell carcinoma (HNSCC). METHODS: Fourteen HNSCC cell lines and four primary tumor specimens were evaluated using immunoblotting, and immunohistochemical analysis was performed on 35 primary HNSCCs. RESULTS: Galectin-1 and galectin-3 were expressed in most HNSCC cell lines and primary tumor specimens. Galectin-1 was detected in the basal layer of normal adjacent mucosa, in connective tissue stroma, and at the periphery of invasive tumor islands. Galectin-3 localized to superficial mucosal layers, and adjacent to keratin pearls in invasive carcinoma. CONCLUSIONS: Galectins are manifested in HNSCC tumors and are localized to the cell surface, where they may participate in cellular interactions. The expression pattern of galectins appears to be associated with degree of squamous differentiation, suggesting a potential role for galectins as biologic and differentiation markers in HNSCC.

Antigens, Differentiation↗

Upregulation of galectins-1 and -3 in human colon cancer and their role in regulating cell migration.

To probe the potential contribution of beta-galactoside-contributing epitopes and receptor proteins (gal-1 and gal-3) to colon malignancy, we first examined the expression of galectins and binding sites in clinical specimens by lectin and immunohistochemistry. Sixty-seven colonic surgical resections were studied, including 10 normal, 10 mild dysplasias, 10 severe dysplasias and 37 cancers. gal-1 and gal-3 were expressed in variable amounts in the epithelial cells and the connective tissue of normal colon. Their expression significantly increased with the degree of dysplasia, suggesting that gal-1 and gal-3 and their binding sites are related to malignant progression, while gal-8 has been associated with suppressor activity. To study the functional aspects, the influence of these galectins on the migration of 4 human colorectal cancer cell lines (HCT-15, LoVo, DLD-1, CoLo201) was studied. In agreement with histopathologic monitoring, these tumor cells were found to produce gal-3, while only CoLo201 was positive for gal-1. Except for DLD-1 and gal-1, the lines exhibited gal-1 binding sites on the surface, prompting study by computer-assisted videomicroscopy of the effect on cell migration of the presence of galectin on the culture substrate. The level of cell migration for HCT-15, LoVo and CoLo201 cells was significantly reduced by 0.15 microg/cm(2) gal-1, and the presence of a blocking antibody at least reduced this effect. gal-3 significantly reduced cell migration in all 4 of the in vitro cell lines.

Adenocarcinoma↗

Determination of structural and functional overlap/divergence of five proto-type galectins by analysis of the growth-regulatory interaction with ganglioside GM1 in silico and in vitro on human neuroblastoma cells.

The growth-regulatory interplay between ganglioside GM1 on human SK-N-MC neuroblastoma cells and an endogenous lectin provides a telling example for glycan (polysaccharide) functionality. Galectin-1 is the essential link between the sugar signal and the intracellular response. The emerging intrafamily complexity of galectins raises the question on defining extent of their structural and functional overlap/divergence. We address this problem for proto-type galectins in this system: ganglioside GM1 as ligand, neuroblastoma cells as target. Using the way human galectin-1 interacts with this complex natural ligand as template, we first defined equivalent positioning for distinct substitutions in the other tested proto-type galectins, e.g., Lys63 vs. Leu60/Gln72 in galectins-2 and -5. As predicted from our in silico work, the tested proto-type galectins have affinity for the pentasaccharide of ganglioside GM1. In contrast to solid-phase assays, cell surface presentation of the ganglioside did not support binding of galectin-5, revealing the first level of regulation. Next, a monomeric proto-type galectin (CG-14) can impair galectin-1-dependent negative growth control by competitively blocking access to the shared ligand without acting as effector. Thus, the quaternary structure of proto-type galectins is an efficient means to give rise to functional divergence. The identification of this second level of regulation is relevant for diagnostic monitoring. It might be exploited therapeutically by producing galectin variants tailored to interfere with galectin activities associated with the malignant phenotype. Moreover, the given strategy for comparative computational analysis of extended binding sites has implications for the rational design of galectin-type-specific ligands.

Amino Acid Sequence↗

Identification of tumor-associated proteins in oral tongue squamous cell carcinoma by proteomics.

Oral tongue carcinoma is an aggressive tumor that particularly affects chronic smokers, drinkers and betel squid chewers. Patients often present symptoms at a late stage, and there is a high recurrence rate after treatment. In this article, we report the first proteomic analysis of oral tongue carcinoma to globally search for tumor related proteins. Apart from helping us to understand the molecular pathogenesis of the carcinoma, these proteins may also have potential clinical applications as biomarkers, enabling the tumor to be identified at an early stage in high risk individuals, treatment response to be predicted, and residual or recurrent carcinoma to be detected sooner after treatment. The protein expression profiles of ten oral tongue squamous cell carcinomas and their matched normal mucosal resection margins were examined by two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization-time of flight mass spectroscopy. A number of tumor-associated proteins including heat shock protein (HSP)60, HSP27, alpha B-crystalline, ATP synthase beta, calgranulin B, myosin, tropomyosin and galectin 1 were consistently found to be significantly altered in their expression levels in tongue carcinoma tissues, compared with their paired normal mucosae. The expression profile portrays a global protein alteration that appears specific to oral tongue cancer. The potential of utilizing these tumor related proteins for screening cancer and monitoring recurrence warrants further investigation.

Adult↗

A comparative nuclear localization study of galectin-1 with other splicing components.

Using both conventional and laser confocal fluorescence microscopy, the intracellular distribution of galectin-1 in HeLa cells was analyzed and compared with the localization of previously documented markers of the nucleus and cytoplasm. The Sm epitopes of the small nuclear ribonucleoprotein complexes (snRNPs) and the non-snRNP splicing factor SC35 yielded only nuclear staining. On the other hand, the enzyme lactate dehydrogenase was cytoplasmic. In contrast to these patterns in which nuclear versus cytoplasmic localizations appeared to be mutually exclusive, galectin-1, as well as galectin-3, yielded simultaneous nuclear and cytoplasmic staining. Confocal microscopy showed galectin-1 fluorescence throughout most of the sections from the top of the cell to the bottom. Through the middle sections, as the plane of focus cuts through the nucleus, there was definite fluorescence staining in the nuclear compartment. This nuclear localization was critically dependent on the type of detergent used to permeabilize the cell: cells treated with saponin or digitonin yielded exclusively cytoplasmic staining while Triton X-100-treated cells showed nuclear as well as cytoplasmic labeling. Finally, double-immunofluorescence analysis showed that, within the nucleoplasm, the following pairs of nuclear antigens could be colocalized in certain speckled structures: (a) SC35 versus Sm; (b) galectin-1 versus Sm; (c) galectin-3 versus Sm; and (d) galectin-1 versus galectin-3. These results establish the presence of galectin-1 in the nuclei of HeLa cells, a conclusion consistent with the identification of the protein in nuclear extracts of the same cells and with its documentation as a factor in pre-mRNA splicing.

Antigens, Differentiation↗

The genomic structure of the human Charcot-Leyden crystal protein gene is analogous to those of the galectin genes.

The Charcot-Leyden crystal (CLC) protein, or eosinophil lysophospholipase, is a characteristic protein of human eosinophils and basophils; recent work has demonstrated that the CLC protein is both structurally and functionally related to the galectin family of beta-galactoside binding proteins. The galectins as a group share a number of features in common, including a linear ligand binding site encoded on a single exon. In this work, we demonstrate that the intron-exon structure of the gene encoding CLC is analogous to those encoding the galectins. The coding sequence of the CLC gene is divided into four exons, with the entire beta-galactoside binding site encoded by exon III. We have isolated CLC beta-galactoside binding sites from both orangutan (Pongo pygmaeus) and murine (Mus musculus) genomic DNAs, both encoded on single exons, and noted conservation of the amino acids shown to interact directly with the beta-galactoside ligand. The most likely interpretation of these results suggest the occurrence of one or more exon duplication and insertion events, resulting in the distribution of this lectin domain to CLC as well as to the multiple galectin genes.

Amino Acid Sequence↗

Inflammation-induced modulation of cellular galectin-1 and -3 expression in a model of rat peritonitis.

OBJECTIVE AND DESIGN: To investigate the effect of galectin-1 (Gal-1) and -3 (Gal-3) on leukocyte migration and analyze the expression of both galectins in inflammatory cells using a model of rat peritonitis. MATERIAL OR SUBJECTS: Sprague-Dawley rats (n = 4 per group). TREATMENT: Peritonitis was induced in animals through intraperitoneal injection of carrageenin (1.5 mg/kg) and rat mesenteries were analyzed at different time points (0, 4, 24 and 48h). For pharmacological treatment, rats received intravenous injection of Gal-1 or -3 (3microg/kg) followed by carrageenin. METHODS: Western blotting and immunoelectron microscopy analysis. Statistical analysis was performed using ANOVA followed by Bonferroni test. RESULTS: Pharmacological treatment with Gal-1, but not Gal-3, inhibited (approximately 50 %) leukocyte recruitment into the peritoneal cavity at 4 h time-point. In this early phase, immunogold staining of mesenteries showed a diminished Gal-3 expression in degranulated mast cells and Gal-1 in transmigrated neutrophils (approximately 20 % reduction compared to intravascular cells). In the later phases (24 and 48h), leukocyte turnover was associated with augmented Gal-1 expression in neutrophils and macrophages and Gal-3 in mast cells and macrophages. CONCLUSIONS: These results point to a balanced expression of cell-associated-Gal-1/Gal-3 and might impact on the development of new therapeutic strategies for inflammatory diseases.

Animals↗

Galectins: versatile modulators of cell adhesion, cell proliferation, and cell death.

Lectins, or carbohydrate binding proteins, recognize specific oligosaccharide structures on glycoproteins and glycolipids. Several families of animal lectins have been identified; for some of these lectins, functions such as leukocyte adhesion and microbial opsonization have been described. The galectins are a family of lectins found in species ranging from sponges and nematodes to humans. Members of the galectin family have been proposed to mediate cell adhesion, to regulate cell growth, and to trigger or inhibit apoptosis. The expression pattern of different galectins changes during development, and this pattern is also altered at sites of inflammation and in breast, colon, prostate, and thyroid carcinomas. In addition, the level of expression of some galectins by tumor cells has been shown to be correlated with metastatic potential. The mechanisms by which galectins exert these diverse effects remain largely unknown. Some glycoprotein counterreceptors recognized by certain galectins have been identified; this is an important first step in understanding the cell-type specific effects of different galectins. This review discusses the way in which the modulation of galectin activity may affect strategies for treatment of a variety of human diseases, including autoimmunity and cancer.

Animals↗

Galectin-1 and galectin-3 expression in human prostate tissue and prostate cancer.

Galectin-1 and galectin-3, two beta-galactoside-binding proteins, have been suggested to play a role in the development and progression of cancer. We have studied the expression of these molecules in normal human prostate tissue and prostate adenocarcinoma. Immunohistochemistry was used to examine formalin-fixed, paraffin-embedded sections of seven normal human prostates, eight cases of prostatic intraepithelial neoplasia (PIN), 20 primary adenocarcinomas of the prostate, and 12 prostate cancer metastases. Galectin-1 was expressed in most cases of all four histologic types. In contrast, galectin-3 expression was significantly decreased in primary carcinoma and metastatic disease compared with normal and premalignant tissue. Galectin-3 expression in primary tumors tended to be less than that of surrounding normal glands. We conclude that loss of galectin-3 expression may be associated with the progression of prostate cancer.

Adenocarcinoma↗

Towards functional glycomics by localization of binding sites for tissue lectins: lectin histochemical reactivity for galectins during diethylstilbestrol-induced kidney tumorigenesis in male Syrian hamster.

Endogenous lectins act as effectors of cellular activities such as growth regulation, migration, and adhesion. Following their immunohistochemical localization in our previous study (Saussez et al. in Histochem Cell Biol 123:29-41, 2005) we purified several galectins and used them as tools for monitoring accessible binding sites. Herein, we report the use of galectin histochemistry for the analysis of diethylstilbestrol (DES)-induced renal tumors in male Syrian hamster kidney (SHKT). Sections of normal kidney and DES-treated kidney were analyzed with biotinylated galectins-1, -3 (full-length and truncated), and -7. Accessible binding sites were detected, localization was predominantly extracellular and confined to medium-sized and large tumors. Monitoring the SHKT-derived HKT-1097 line, processed in vitro or as xenograft material, cytoplasmic and nuclear staining for galectins-1, -3, and -3tr could be observed. Adaptation of SHKT cells to long-term growth in culture is thus associated with emergence of this signal. Our data set illustrates the feasibility to complement immunohistochemical data by application of the tissue lectins as probes, and to detect regulation of galectin reactivity with differential characteristics within tumor progression in vivo and unique features of the tumor cell line in vitro and in vivo.

Animals↗

Immunohistochemical distribution of galectin-1, galectin-3, and olfactory marker protein in human olfactory epithelium.

The expression pattern of galectin-1 and galectin-3 in the human olfactory epithelium was investigated in relation to olfactory marker protein (OMP) using confocal laser immunofluorescence in human specimens and postmortem biopsies. OMP expression was found in olfactory receptor neurons (ORNs) in the olfactory mucosa and in fibers of the olfactory nerve crossing the submucous connective tissue. Galectin-1 was expressed in both the connective tissue of the nasal cavity and in the basal layer of the olfactory epithelium. In contrast, galectin-3 expression was limited to cells of the upper one-third of the olfactory epithelium. Expression of galectin-3 occurred in a subset of OMP-positive cells. However, between areas of galectin-1 and galectin-3 expression in the lower and upper portion of the epithelium, OMP-positive ORNs did not stain for both galectins. Considering the potential role of galectin-1 and galectin-3 in cell differentiation and maturation, the differential localization of galectins in the olfactory epithelium appears to be consistent with a significant role of these molecules in the physiological turnover of ORNs.

Adolescent↗

Comprehensive galectin fingerprinting in a panel of 61 human tumor cell lines by RT-PCR and its implications for diagnostic and therapeutic procedures.

PURPOSE: Knowledge about galectin expression by human tumor cells is mainly restricted to galectins-1 and -3. This study was conducted to define the gene expression pattern of all presently known human galectins in tumor cell lines of various histogenetic origin (galectinomics). METHODS: The presence of mRNAs for human galectins-1, -2, -3, -4, -7, -8, and -9 was monitored by RT-PCR analyses in a panel of 61 human tumor cell lines of different origin (breast, colon, lung, brain, skin, kidney, urogenital system, hematopoietic system). RESULTS: The validity of the technique was first confirmed by comparison of RT-PCR data with those obtained by Western blotting and cytofluorometry for galectins-1 and -3 in 18 cell lines. The following detection of a complex pattern of gene expression beyond commonly studied galectins-1 and -3 underscored the need for this fingerprinting. The most abundantly expressed message for a member of this lectin family was galectin-8 with 59 positive cell lines. With the exception of the tested lung tumors, galectin-1 and -3 transcripts were frequently expressed in the cell line panel with differences between individual cases. Positivity for galectins-2 and -4 was confined to a significant fraction of colorectal and neural tumors. Signals for galectin-9, the third known human tandem-repeat-type galectin besides -4 and -8, appeared in colorectal carcinoma cell lines with a frequency similar to that of galectin-4 but with inter-line differences. Its expression was restricted to lines of this tumor type, of the tested ovarian carcinoma, and hematopoietic malignancies. CONCLUSIONS: The results clearly demonstrate that human tumor cells express more mRNA species for galectins than those for galectins-1 and -3. To derive unequivocal diagnostic and prognostic information by immunohistochemistry on galectins with antagonistic impact on growth control and significant influence on cell adhesion, additional monitoring of these so far insufficiently studied family members is essential.

Antigens, Differentiation↗

Galectin-1 and galectin-3 in fetal development of bovine respiratory and digestive tracts. Comparison of cell type-specific expression profiles and subcellular localization.

Histochemical monitoring of developmental processes is presently centered on protein-protein interactions. However, oligosaccharides have the potential to store and transmit biological information. Carbohydrate chains of cellular glycoconjugates present determinants for binding of endogenous lectins. This interaction can be relevant for developmental processes. In fact, beta-galactosides and their derivatives serve as ligands for members of the lectin family of galectins. Since it is unclear to what extent functions of different galectins differ or overlap, hereby introducing redundancy into this system, monitoring of galectin presence during tissue maturation should include more than one type of galectin (galectin fingerprinting). Here, we focus on the two most frequently described ones, namely the homodimeric prototype galectin-1 and the chimera-type galectin-3, the latter one so far not characterized from bovine tissue. In the first step, we have detected its presence biochemically in addition to the abundant galectin-1 in bovine respiratory and digestive tracts during development. Evidently, diversification of the primitive foregut will not lead to an alteration of this property. Immunohistochemistry revealed clear differences in the galectins' localization profiles. Galectin-1 expression is strong in mesenchymal cells, especially smooth muscle cells, while epithelial lining harbors galectin-3. A gradual increase in staining intensity with development is especially observed in the case of galectin-3. Notably, this change is accompanied by a shift from primarily nuclear localization to the cytoplasm, an alteration not seen for galectin-1. However, nuclear presence of galectin-1 is encountered. Thus, the delineation of differences in expression of galectin-1 and -3 with respect to cell types and in the developmental course of subcellular localization argues in favor of mediation of nonoverlapping functions by these two homologous, endogenous lectins.

Animals↗

Galectin-3 mRNA level depends on transformation phenotype in ras-transformed NIH 3T3 cells.

The increase in galectin-3 lectin content observed in tumours or in in vitro transformed cells suggests that this lectin is important in the transformation process. In the present study, we investigated the mRNA expression level of the galectin-3, galectin-1 and macrophage mannose receptor in normal and ras-transformed NIH 3T3 cells in relation to their transformation state. The galectin-3 mRNA content in ras-transformed cells is increased in fully transformed cells, with a maximum in ras-transformed cells that have lost their growth anchorage-dependence. Under the same conditions, the galectin-1 mRNA level which was high in normal cells, increased slightly in transformed cells. The mRNA for the macrophage mannose receptor was not detected in 3T3 cells or in their ras-transformed counterparts.

3T3 Cells↗

Fluorescence polarization as an analytical tool to evaluate galectin-ligand interactions.

Galectins are a family of beta-galactose binding lectins associated with functions such as immunological and malignant events. To study the binding affinity of galectins for natural and artificial saccharides and glycoconjugates we have developed an assay using fluorescence polarization. A collection of fluorescein-conjugated saccharides was synthesized and used as probes with galectins-1 and -3 and the two carbohydrate recognition domains of galectin-4. Direct binding of a fixed probe amount with different amounts of each galectin defined specificity and selectivity and permitted selection of the optimal probe for inhibition studies. Then fixed amounts of galectin and selected probe were used to screen the inhibitory potency of a library of nonfluorescent compounds. As the assay is in solution and does not require separation of free and bound probe, it is simple and rapid and can easily be applied to different unlabeled galectins. As all interaction components are known, K(d) values for galectin-inhibitor interaction can be directly calculated without approximation other than the assumption of a simple one-site competition.

Animals↗

Proteomics-based identification of secreted protein dihydrodiol dehydrogenase as a novel serum markers of non-small cell lung cancer.

Identification of secreted proteins of lung cancer could provide new candidates of serum biomarkers for cancer diagnosis and prognosis evaluation. In this study, non-small cell lung cancer (NSCLC) cell line A549 was cultured. Proteins in the conditioned medium of A549 were recovered and the proteome analysis was subsequently performed. Secreted proteins of A549 were identified using mass spectrometry and database search. Fourteen human proteins were identified, including peptidyl-prolyl cis-trans isomerase A, manganese superoxide dismutase, peroxiredoxin 1, phosphatidylethanolamine-binding protein, glutathione S-transferase P, PGP9.5, alpha enolase, phosphoglycerate mutase 1, galectin-1 and dihydrodiol dehydrogenase (DDH). DDH was selected for further analysis using RT-PCR, immunoblotting, immunohistochemical staining and ELISA in NSCLC patients. Compared with normal lung tissues, higher DDH mRNA and protein expression level were found in 15 NSCLC cancer tissues (p<0.05). DDH overexpression was identified to be located in cytoplasm and cell membrane by immunohistochemical staining in NSCLC tissue. The serum level of DDH was significantly higher in NSCLC patients (n=64) than nonmalignant lung tumor (n=20) and healthy controls (n=20) (p<0.05). The results show that DDH was one of the secreted proteins in NSCLC. It can serve as a tissue marker and a novel serological marker of NSCLC. Identification of secreted proteins could be a feasible and effective strategy to search potential serum biomarkers of cancer.

Aged↗