Galectin-3 is strongly up-regulated in nonapoptosing mammary epithelial cells during rat mammary gland involution.
TL;DR: The data suggest that the up-regulation of galectin-3 in the involuting mammary gland is not only controlled transcriptionally but also regulated posttranscriptionally under the control of systemic glucocorticoid hormones involved in coordinating the involution process.
Abstract: Galectin-3 is an endogenous mammalian lectin that binds to ABH carbohydrate antigens. Here we show that galectin-3 is strongly up-regulated during mammary gland involution and that it is expressed virtually exclusively on nonapoptotic cells. We demonstrate that dexamethasone, an inhibitor of the second phase of mammary gland involution, potently suppresses up-regulation of galectin-3 as judged immunohistochemically and on western blots, suggesting that systemic hormone levels regulate galectin-3 expression during involution. However, at the RNA level galectin-3 expression is rapidly up-regulated on the onset of involution but remains consistantly high during the first and second phase of involution regardless of dexamethasone treatment. These data suggest that the up-regulation of galectin-3 in the involuting mammary gland is not only controlled transcriptionally but also regulated posttranscriptionally under the control of systemic glucocorticoid hormones involved in coordinating the involution process.
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29 Oct 2001
43 citations
TL;DR: This review will summarise recent progress in defining the roles of galectins that are expressed in the kidney in normal development, and discuss the evidence linking aberrant expression of galECTins with kidney disease.
Abstract: Galectins are a family of proteins with overlapping but distinct carbohydrate-binding specificities. They differ in cell-type and tissue distribution, and have various functions. Extracellularly several galectins can modulate cellular adhesive interactions and signalling pathways, effects that may be important in the establishment and maintenance of tissue organization during normal development. This review will summarise recent progress in defining the roles of galectins that are expressed in the kidney in normal development, and discuss the evidence linking aberrant expression of galectins with kidney disease.
42 citations
TL;DR: Tumor hypoxia up-regulates the expression of galectin-3, which may in turn increase tumor aggressiveness, as well as promoting angiogenesis, cell proliferation and resistance to apoptosis.
Abstract: 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.
37 citations
Cites background from "Galectin-3 is strongly up-regulated..."
...This may imply that galectin-3 expression is regulated both at the transcriptional and post-transcriptional levels [7, 32]....
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TL;DR: It is hypothesized that loss of galectin-3 and sialylation-related masking of its ligands, in conjunction with their overexpression in specific tumour cell subpopulations, are crucial in regulating adhesive/de-adhesive events in the progression and invasive capacity of metastatic cells.
Abstract: Galectin-3 is involved both in facilitating detachment of cells from primary tumour sites and favouring cancer cell adhesion and survival to anoikis in the blood stream. The mechanisms behind these apparently contradictory roles of the lectin have not yet been resolved. In order to investigate possible interplays between galectin-3 and its ligands underlying their role in the metastatic process, we examined mucin-1 (MUC1) and epidermal growth factor receptor (EGFR), well-known galectin-3 ligands, as well as galectin-3-binding site expression in a series of spontaneous canine malignant mammary tumours (CMMT) and a metastatic CMMT cell line. Despite the fact that CMMT cells expressed MUC1 and EGFR homogeneously over their plasma membrane, intravascular tumour cells, positive for galectin-3, expressed MUC1 and EGFR in a more focal membrane localization. Moreover, MUC1 overexpression in primary CMMT was present in parallel with down-regulation of galectin-3. Furthermore, in the CMT-U27 cell line, galectin-3 knock-down led to increased MUC1 expression, while MUC1 knock-down led to down-regulation of the lectin. Finally, removal of sialic acid from both CMMT and CMT-U27 xenograft samples exposed galectin-3-ligands throughout the tumour tissue, whereas these ligands were only present in galectin-3-positive invading cells in untreated samples. Interestingly indeed, we show that in vessel-invading cells, there is interaction between galectin-3 and the T antigen in vivo. We therefore hypothesized that loss of galectin-3 and sialylation-related masking of its ligands, in conjunction with their overexpression in specific tumour cell subpopulations, are crucial in regulating adhesive/de-adhesive events in the progression and invasive capacity of metastatic cells.
34 citations
Cites background from "Galectin-3 is strongly up-regulated..."
...Furthermore, in normal lactating mammary glands sialyltransferase ST6GalI expression is increased (Dalziel et al., 2001) while galectin-3 is down-regulated (Mengwasser et al., 2002)....
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..., 2001) while galectin-3 is down-regulated (Mengwasser et al., 2002)....
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TL;DR: Analysis of the results established that the galectin coating the membrane, by galactoside recognition of the breast cells, and engaged by the cells to form protein-carbohydrate complexes inside the microfluidic assay, resembled the tumour signature of tumours in breast cells whilst the galECTin free is independent of those mechanisms.
Abstract: Galectin-3, β-galactoside-binding lectin, coats the membrane of most cancer cells and is involved in metastasis and endothelium recognition as well as in evading immune surveillance through killing of activated T cells. To flag galectin as a biomarker of tumours and metastasis, it is pivotal to understand the role of this protein in different tumours and at different stages. Breast tumours have an anomalous behaviour of the galectin-3 compared to other tumour cells. Herein, FACS sorting and galactoside based assays were used to investigate the role of galectin-3 in metastasis and metastatisation of breast cancer cells. Breast galectin fingerprint at the FACS displayed a higher amount in healthy cells, compared to metastatic cells. The microfluidic assay was able to isolate tumour and metastatic cells more than healthy breast cells. Investigation was performed on samples from patients with breast tumours at stage I and stage III whilst MCF7 and EPH-4 cells were used to perform preliminary investigations. The readout of the conditioned medium (from culturing of stage I cells) fingerprint by FACS evidenced high expression of free galectin. Analysis of the results established that the galectin coating the membrane, by galactoside recognition of the breast cells, and engaged by the cells to form protein–carbohydrate complexes inside the microfluidic assay, resembled the tumour signature of tumours in breast cells whilst the galectin free is independent of those mechanisms.
24 citations
References
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TL;DR: A method has been devised for the electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets that results in quantitative transfer of ribosomal proteins from gels containing urea.
Abstract: A method has been devised for the electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets. The method results in quantitative transfer of ribosomal proteins from gels containing urea. For sodium dodecyl sulfate gels, the original band pattern was obtained with no loss of resolution, but the transfer was not quantitative. The method allows detection of proteins by autoradiography and is simpler than conventional procedures. The immobilized proteins were detectable by immunological procedures. All additional binding capacity on the nitrocellulose was blocked with excess protein; then a specific antibody was bound and, finally, a second antibody directed against the first antibody. The second antibody was either radioactively labeled or conjugated to fluorescein or to peroxidase. The specific protein was then detected by either autoradiography, under UV light, or by the peroxidase reaction product, respectively. In the latter case, as little as 100 pg of protein was clearly detectable. It is anticipated that the procedure will be applicable to analysis of a wide variety of proteins with specific reactions or ligands.
53,030 citations
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...P (Millipore) by the method of Towbin et al. (1979)....
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TL;DR: Galectin-3 is a regulator of cell growth and apoptosis and it may function through a cell death inhibition pathway that involves Bcl-2, a well-characterized suppressor of apoptosis.
Abstract: Galectin-3 is a member (if a large family of beta-galactoside-binding animal lectins. It has been shown that the expression of galectin-3 is upregulated in proliferating cells, suggesting a possible role for this lectin in regulation of cell growth. Previously, we have shown that T cells infected with human T-cell leukemia virus type I express high levels of galectin-3, in contrast to uninfected cells, which do not express detectable amounts of this protein. In this study, we examined growth properties of human leukemia T cells transfected with galectin-3 cDNA, and thus constitutively overexpressing this lectin. Transfectants expressing galectin-3 displayed higher growth rates than control transfectants, which do not express this lectin. Furthermore, galectin-3 expression in these cells confers resistance to apoptosis induced by anti-Fas antibody and staurosporine. Galectin-3 was found to have significant sequence similarity with Bcl-2, a well-characterized suppressor of apoptosis. In particular, the lectin contains the NWGR motif that is highly conserved among members of the Bcl-2 family and shown to be critical for the apoptosis-suppressing activity. We further demonstrated that galectin-3 interacts with Bc1-2 in a lactose-inhibitable manner. We conclude that galectin-3 is a regulator of cell growth and apoptosis and it may function through a cell death inhibition pathway that involves Bcl-2.
750 citations
"Galectin-3 is strongly up-regulated..." refers background in this paper
...Additionally it has anti-apoptotic and growth-enhancing properties (Yang et al., 1996; Akahani et al., 1997) and can promote cell invasiveness (Le Marer and Hughes, 1996)....
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TL;DR: Questions remain largely unanswered but recent studies are beginning to give glimpses into some novel aspects of the secretion of galectins, including their role as modulators of cell adhesion and signalling.
619 citations
"Galectin-3 is strongly up-regulated..." refers background in this paper
...Galectin-3 is an endogenous mammalian lectin that binds to ABH antigens (Sato and Hughes, 1992), and can be located in the cytoplasm, located in the nucleus, or secreted extracellularly (reviewed in Hughes, 1999)....
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TL;DR: Wyllie et al. as discussed by the authors showed that post-lactational mammary gland involution results in a dramatic drop in ODC, a gene involved in synthesis of a component of milk, and nearly simultaneous induction of SGP-2, associated with apoptotic cell death.
Abstract: During post-lactational mammary gland involution, the bulk of mammary epithelium dies and is reabsorbed. This massive cell death and tissue restructuring was found to be accompanied by a specific pattern of gene expression. Northern blot analysis showed that weaning resulted in a dramatic drop in ODC, a gene involved in synthesis of a component of milk, and the nearly simultaneous induction of SGP-2, a gene associated with apoptotic cell death. These changes were followed by decreases in expression of milk protein genes to basal levels and expression of genes associated with regulation of cell proliferation and differentiation, p53, c-myc and TGF-beta 1. Subsequently, additional genes implicated in stress response, tissue remodelling, and apoptotic cell death were transiently expressed, expression peaking at about 6 days post-weaning. A non-random degradation of DNA yielding the oligonucleosomal length fragmentation pattern typical of apoptotic cell death (Wyllie, 1980; Wyllie et al., 1980) was detected in association with morphological changes and gene expression. The correlations between: (a) changes in morphology, (b) pattern of gene expression and (c) changes in DNA integrity suggest that complementary programs for cell death and tissue remodelling direct post-lactational mammary gland involution.
531 citations
"Galectin-3 is strongly up-regulated..." refers background in this paper
...During involution the mammary gland is restructured through the coordinated processes of apoptosis of luminal epithelial, myoeptithelial, and endothelial cells, and lobular-alveolar remodeling (Pitelka, 1988; Lund et al., 1996; Strange et al., 1992)....
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TL;DR: The data support the hypothesis that there are at least two distinct phases of involution: an initial phase, characterized by induction of the apoptosis-associated genes SGP-2 and ICE and apoptosis of fully differentiated mammary epithelial cells without visible degradation of the extracellular matrix, and a second phase, characterize by extrace cellular matrix remodeling and altered mesenchymal-epithelial interactions, followed by apoptotic cells that are losing differentiated functions.
Abstract: Postlactational involution of the mammary gland is characterized by two distinct physiological events: apoptosis of the secretory, epithelial cells undergoing programmed cell death, and proteolytic degradation of the mammary gland basement membrane. We examined the spatial and temporal patterns of apoptotic cells in relation to those of proteinases during involution of the BALB/c mouse mammary gland. Apoptosis was almost absent during lactation but became evident at day 2 of involution, when beta-casein gene expression was still high. Apoptotic cells were then seen at least up to day 8 of involution, when beta-casein gene expression was being extinguished. Expression of sulfated glycoprotein-2 (SGP-2), interleukin-1 beta converting enzyme (ICE) and tissue inhibitor of metalloproteinases-1 was upregulated at day 2, when apoptotic cells were seen initially. Expression of the matrix metalloproteinases gelatinase A and stromelysin-1 and the serine proteinase urokinase-type plasminogen activator, which was low during lactation, was strongly upregulated in parallel starting at day 4 after weaning, coinciding with start of the collapse of the lobulo-alveolar structures and the intensive tissue remodeling in involution. The major sites of mRNA synthesis for these proteinases were fibroblast-like cells in the periductal stroma and stromal cells surrounding the collapsed alveoli, suggesting that the degradative phase of involution is due to a specialized mesenchymal-epithelial interaction. To elucidate the functional role of these proteinases during involution, at the onset of weaning we treated mice systemically with the glucocorticoid hydrocortisone, which is known to inhibit mammary gland involution. Although the initial wave of apoptotic cells appeared in the lumina of the gland, the dramatic regression and tissue remodeling usually evident by day 5 was substantially inhibited by systemic treatment with hydrocortisone. mRNA and protein for gelatinase A, stromelysin-1 and uPA were weakly induced, if at all, in hydrocortisone-treated mice. Furthermore, mRNA for membrane-type matrix metalloproteinase decreased after hydrocortisone treatment and paralleled the almost complete inhibition of activation of latent gelatinase A. Concomitantly, the gland filled with an overabundance of milk. Our data support the hypothesis that there are at least two distinct phases of involution: an initial phase, characterized by induction of the apoptosis-associated genes SGP-2 and ICE and apoptosis of fully differentiated mammary epithelial cells without visible degradation of the extracellular matrix, and a second phase, characterized by extracellular matrix remodeling and altered mesenchymal-epithelial interactions, followed by apoptosis of cells that are losing differentiated functions.
526 citations
"Galectin-3 is strongly up-regulated..." refers background in this paper
...In the second phase, proteases degrade extracellular matrix and basement membrane components and the lobular-alveolar structures collapse (Lund et al., 1996)....
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...Additionally, dexamethasone treatment inhibits tissue remodeling but not apoptosis in involuting mammary glands (Lund et al., 1996; Li et al., 1997; Mengwasser and Sleeman, 2001; data presented herein) and also suppresses galectin-3 expression (Figure 3, Figure 5, Table II)....
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...Glucocorticoid hormones have been reported to be able to inhibit the second stage of involution in postlactating animals (Lund et al., 1996; Li et al., 1997; Mengwasser and Sleeman, 2001)....
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...…stages, a first reversible stage controlled by local factors in which alveolar structure remains intact, and a second stage dependent on systemic hormone levels, characterized by alveolar collapse and tissue remodeling and that begins around 4 days postweaning (Lund et al., 1996; Li et al., 1997)....
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...Mammary involution occurs in two stages, a first reversible stage controlled by local factors in which alveolar structure remains intact, and a second stage dependent on systemic hormone levels, characterized by alveolar collapse and tissue remodeling and that begins around 4 days postweaning (Lund et al., 1996; Li et al., 1997)....
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