Galectin-3 Protects Human Breast Carcinoma Cells against Nitric Oxide-Induced Apoptosis : Implication of Galectin-3 Function during Metastasis

Galectin-3 is a beta-galactoside-binding protein which regulates many biological processes including cell adhesion, migration, cell growth, tumor progression, metastasis, and apoptosis. Although the exact function of galectin-3 in cancer development is unclear, galectin-3 expression is associated with neoplastic progression and metastatic potential. Since studies have suggested that tumor cell survival in microcirculation determines the metastatic outcome, we examined the effect of galectin-3 overexpression in human breast carcinoma cell survival using the liver ischemia/reperfusion metastasis model. While the majority of control cells died by hepatic ischemia/reoxygenation, nearly all of galectin-3 overexpressing cells survived. We showed that galectin-3 inhibits nitrogen free radical-mediated apoptosis, one of the major death pathways induced during hepatic ischemia/reperfusion. Galectin-3 inhibition of apoptosis involved protection of mitochondrial integrity, inhibition of cytochrome c release and caspase activation. Taking these results together with the previous observation that galectin-3 inhibits apoptosis induced by loss of cell adhesion, we propose that galectin-3 is a critical determinant for anchorage-independent and free radical-resistant cell survival during metastasis.     

Immunohistochemical galectin-3 expression in non-melanoma skin cancers

Galectin-3 is a ss-galactoside-binding lectin. It participates in a variety of normal and pathologic processes, including cancer progression. In this study, we evaluated the pattern of expression of galectin-3 in cutaneous squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), and its correlation with the grade of differentiation in SCC and tumor size. Galectin-3 expression was evaluated by immunohistochemistry in 31 SCCs, 30 BCCs, and 29 non-tumoral skin samples. Galectin-3 expression was higher in normal epidermis than in non-melanoma skin cancers, except for cytoplasmic immunoreactivity in SCC. Cytoplasmic galectin-3 immunoreactivity was significantly higher than nuclear immunoreactivity in non-melanoma skin cancers. Cytoplasmic galectin-3 immunoreactivity was significantly higher in SCC than in both circumscribed and infiltrative BCCs, but no difference was detected between these two types of BCC. Cytoplasmic galectin-3 immunoreactivity predominated within SCCs (p=0.000), and a positive correlation was detected between tumor size and cytoplasmic immunoreactivity (r=0.385, p=0.043). There was no correlation between galectin-3 staining and tumor differentiation and lymph node metastasis. Decreased nuclear galectin-3 expression and cytoplasmic immunoreactivity in tumors are important factors in the progression from the normal to the cancerous state in non-melanoma skin cancers. We speculate that cytoplasmic galectin-3 expression may be one of the factors that contribute to tumor aggressiveness in SCC.     

Galectin-3 Expression in Tumor Progression and Metastasis of Papillary Thyroid Carcinoma

Galectin-3 plays important roles in cell adhesion, cell proliferation, apoptosis, neoplastic transformation, and metastasis. Galectin-3 expression has been evaluated in various malignant neoplasms to determine its effectiveness in differential diagnosis from benign lesions and its effects on carcinogenesis. There are few and somewhat controversial results regarding its changes through cancer progression in thyroid malignancies. We studied the presence of galectin-3 expression immunohistochemically and its relation with tumor invasiveness and lymph node metastasis in 89 cases of papillary carcinoma of the thyroid. Galectin overexpression was less frequent in cases with lymph node metastases compared with cases without lymph node metastasis (P = 0.001). Metastatic foci in lymph nodes showed a lower degree of galectin-3 overexpression than their primary lesions (P = 0.001). Degree of galectin-3 overexpression was also lower in larger tumors (P = 0.009). Additionally, a decreased level of galectin-3 overexpression was observed at the invasive edges of the tumors (P = 0.001). Galectin-3 overexpression is more profound in early stages of papillary carcinoma, and its expression intensity decreases during tumor progression. This finding is consistent with roles for galectin-3 in cell adhesion to other tumor cells and the matrix.     

Serum levels of galectin-3 and its ligand 90k/mac-2bp in colorectal cancer patients

Galectin-3 is an endogenous lectin that binds glycan epitopes of cell membrane and some extracellular glycoproteins such as integrins and laminin. Galectin-3 is involved in several biological activities including regulation of cellular cycle, modulation of adhesion and tumor progression and metastasis. 90K/Mac-2BP glycoprotein is also a serum galectin-3 ligand. 90K is able to modulate the immune reaction against tumors and viruses and its level increases in sera of several neoplastic diseases. In our study, we have evaluated levels of both glycoproteins in sera of non metastatic colon cancer patients. Interestingly, galectin-3 ranged higher in cancer patients than in controls (p<0.0001), particularly in more differentiated tumors (p<0.04). Moreover, 90K mean values ranged higher in right-side than in left-side colon cancer. In conclusion, serum galectin3 might represent a useful biomarker to evaluate colon cancer transformation and, together with its ligand 90K, could contribute to the characterization of colon cancer.     

Galectin-3 induces endothelial cell morphogenesis and angiogenesis

Increasing evidence suggests that carbohydrate-binding proteins play an essential role in tumor growth and metastasis. However, conflicting results on their function in the regulation of cell proliferation and differentiation during angiogenesis have been reported. We have examined the role of galectin-3 in the regulation of human umbilical vein endothelial cell proliferation, differentiation, migration, and neovascularization. Galectin-3, a carbohydrate-binding protein, with specificity for type 1 and 11 ABH blood group epitopes and polylactosamine glycan containing cell surface glycoproteins, is the major nonintegrin cellular laminin-binding protein. Because galectin-3 expression was shown to be associated in some tumor systems with metastasis, we questioned whether it induces endothelial cell morphogenesis. Here we show that galectin-3 affects chemotaxis and morphology and stimulates capillary tube formation of HUV-EC-C in vitro and angiogenesis in vivo. Endothelial cell morphogenesis is a carbohydrate-dependent process, as it is neutralized by specific sugars and antibodies. These findings demonstrate that endothelial cell surface carbohydrate recognition event(s) can induce a signaling cascade leading to the differentiation and angiogenesis of endothelial cells.     

Gene-expression signature of adhesion/growth-regulatory tissue lectins (galectins) in transitional cell cancer and its prognostic relevance

AIMS: Lectins, and especially galectins, appear to be important in malignancy-associated processes. The aim was to analyse comprehensively the presence of galectins in urothelial tumours. METHODS AND RESULTS: Non-cross-reactive antibodies against seven family members from the three subgroups (prototype: galectin-1, -2 and -7; chimera type: galectin-3; tandem-repeat type: galectin-4, -8 and -9) were used. Gene expression was monitored in specimens of normal urothelium, fresh tumour tissue and cell lines by real-time polymerase chain reaction (PCR). The presence and evidence of tumour-associated up-regulation were shown for galectin-1 and -3. This was less clear-cut for galectin-4 and -8. Galectin-7 was expressed in all cell lines; galectin-2 and -9 were detected at comparatively low levels. Galectin-2, -3 and -8 up-regulation was observed in superficial tumours, but not in muscle-invasive tumours (P < 0.05). Immunoreactivity correlated with tumour grading for galectin-1, -2 and -8, and disease-dependent mortality correlated with galectin-2 and -8 expression. Binding sites were visualized using labelled galectins. CONCLUSIONS: The results demonstrate a complex expression pattern of the galectin network in urothelial carcinomas. Galectin-1, -2, -3 and -8 are both potential disease markers and also possible targets for bladder cancer therapy.     

An antibody to p16INK4A recognizes a modified form of galectin-3.

Galectin-3 is a carbohydrate binding protein involved in multiple processes including cell-cycle regulation and apoptosis. The ability of galectin-3 to protect cells from apoptosis is dependent upon a region of the protein known as a BH-1 domain for its homology to the anti-apoptotic protein Bcl-2. Here, we show that a monoclonal antibody (MAb) to the human tumor suppressor protein p16INK4A recognizes a post-translationally modified form of human galectin-3. The modified form is detectable in only a subset of cell types expressing galectin-3, indicating that the modification is cell-type-specific. Although there is little amino acid sequence homology between p16INK4a and galectin-3, we show by epitope mapping that the modification directly affects the structure of galectin-3's BH-1 domain. Elucidation of the nature of this modification might provide further insight into galectin-3 function.     

Expression of galectin-1 and galectin-3 in renal cell carcinoma; immunohistochemical study

Background and aimsGalectins comprise a large family of calcium independent lectins. Galectin-1 and galectin-3 contribute to neoplastic transformation, angiogenesis, and tumor metastasis in some cancers. This study aimed at studying the immunohistochemical expression of both galectin-1 and galectin-3 in renal cell carcinoma (RCC) variants and detecting the possible association of galectins with various clinicopathological parameters.Materials and methodsSections from 67 formalin-fixed paraffin-embedded tissue blocks of RCC variants were stained with galectin-1 and galectin-3. Expression was assessed in tumor tissue and adjacent renal parenchyma and was correlated with clinicopathological criteria.ResultsIn apparently normal renal parenchyma adjacent to tumor tissue, galectin-1 was expressed in 27 (40.2%) of specimens in renal tubules and glomeruli, while 34 (50.7%) of specimens showed galectin-3 expression in renal tubules sparing glomeruli. In tumor tissue, galectin-1 showed high expression in 47 (70.1%) and low expression in 20 (29.9%) of specimens. Galectin-3 had high expression in 15 (22.4%) and low expression in 52 (77.6%) of specimens. Significant association was detected between expression of galectin-1 and galectin-3 and the type of RCC (P = 0.032) and (P = 0.006), respectively. Significant inverse association was detected between the expression of galectin-3 and the presence of tumor haemorrhage and necrosis (P = 0.014) and (P = 0.039), respectively.ConclusionGalectin-1 and galectin-3 are overexpressed in RCC with different percentage in different subtypes. Galactin-1expression is more in tumor tissue than surrounding renal parenchyma suggesting that it has a carcinogenic role. Galectin-1 and galectin-3 overexpression in chromophobe RCC suggests that they may have diagnostic role.     

The galectin profile of the endothelium: altered expression and localization in activated and tumor endothelial cells

We previously identified overexpression of galectin-1 in activated tumor endothelium. Currently, the tumor vasculature is a target for therapeutic approaches. Little is known about galectin expression and regulation in the tumor vasculature. Here, we report the expression of galectin-1/-3/-8/-9 in the endothelium as determined by quantitative PCR, Western blot, flow cytometry, and immunohistochemistry. Galectin-2/-4/-12 were detectable at the mRNA level, albeit very low. Galectin-8 and -9 displayed alternative splicing. Immunohistochemistry of normal tissues revealed a broad but low expression of galectin-1 in the vasculature, whereas the expression levels and localization of the other galectins varied. Endothelial cell activation in vitro significantly increased the expression of galectin-1 (5.32 +/- 1.97; P = 0.04) and decreased the expression of both galectin-8 (0.59 +/- 0.12; P < 0.04) and galectin-9 (0.32 +/- 0.06; P < 0.002). Galectin-3 expression was unaltered. Although a portion of these proteins is expressed intracellularly, the membrane protein level of galectin-1/-8/-9 was significantly increased on cell activation in vitro, 6-fold (P = 0.005), 3-fold (P = 0.002), and 1.4-fold (P = 0.04), respectively. Altered expression levels and cellular localization was also observed in vivo in the endothelium of human tumor tissue compared with normal tissue. These data show that endothelial cells express several members of the galectin family and that their expression and distribution changes on cell activation, resulting in a different profile in the tumor vasculature. This offers opportunities to develop therapeutic strategies that are independent of tumor type.     

Inhibiting galectin-1 reduces murine lung metastasis with increased CD4(+) and CD8 (+) T cells and reduced cancer cell adherence

Galectin-1 is a β-galactoside-binding protein overexpressed by cancer cells. The primary roles of galectin-1 in cancer progression and metastasis are attributed to suppression of T cell immune responses, promotion of tumor angiogenesis and increased tumor cell adhesion and invasion. Using pulmonary metastasis models of murine breast (4T1) and colon (CT26) cancer, we demonstrate that targeting galectin-1 with thiodigalactoside (TDG) or shRNA galectin-1 knockdown (G1KD) results in a significant reduction in lung metastasis. Increased numbers of CD4(+) helper T cells and CD8(+) cytotoxic T lymphocytes were found in the peripheral blood of both TDG-treated and G1KD cell challenged mice. The levels of TUNEL(+) apoptotic cancer cells and the presence of CD3(+) T cells were also increased in lung metastases. Furthermore, galectin-1 was found to bind to the adhesion molecules, CD44 and CD326, which are also known as markers of breast and colon cancer stem cells, and TDG likely blocks galectin-1 binding to these molecules. The TDG-mediated inhibition of galectin-1 binding reduced 4T1 cell adhesion to the basement membrane protein laminin, Matrigel and EAhy926 endothelial cell surfaces. These findings establish possible mechanisms for the anti-metastatic effect of galectin-1 inhibition and suggest that targeting galectin-1 may represent a promising and effective anti-metastatic therapy.     

Galectin-3 expression correlates with apoptosis of tumor-associated lymphocytes in human melanoma biopsies

The immune system recognizes diverse melanoma antigens. However, tumors can evade the immune response, therefore growing and progressing. It has been reported that galectin-3 and galectin-1 can induce apoptosis of activated lymphocytes. However, there is strong evidence indicating that the regulation of galectins function in the human tumor microenvironment is a complex process that is influenced by diverse biological circumstances. Here, we have investigated 33 biopsies (eight primary and 25 metastases) from 24 melanoma patients (15-72 years old) and describe the correlation between the expression of galectin-3 or galectin-1 and the level of apoptosis of tumor-associated lymphocytes using immunohistochemistry and an in situ nick translation assay. The range of galectin-3-positive tumor cells varied between 0% and 93% and that of galectin-1-positive tumor cells varied between 5% and 97%. In addition, 23 +/- 27% of tumor-associated lymphocytes were apoptotic. Although our results show a correlation between galectin-3 expression and apoptosis of tumor-associated lymphocytes, we could not find such correlation with galectin-1. Considering the complex process of cancer immunoediting, various interacting factors must be considered.     

Galectin-3的抗凋亡机制及其在肺癌中的研究

半乳凝素-3(Galectin-3,Gal-3)是糖结合蛋白家族中的一员,能与β-半乳糖苷特异性结合,参与许多生理和病理过程,在调解细胞生长与分化、机体免疫、细胞黏附、炎症反应、细胞凋亡、血管侵袭等诸多方面起着重要的作用,且与肿瘤的侵袭、转移及预后有关.目前,在许多恶性肿瘤中都发现了Galectin-3的表达,如胃癌、结肠癌、乳腺癌、膀胱癌、甲状腺癌.但在不同的肿瘤中,Galectin-3的表达水平不同.在一些肿瘤中,Galectin-3表达增高,而在某些肿瘤中其表达降低,且其亚细胞定位与肿瘤的发生、发展密切相关.     

Immunhistochemical expression of galectin-3 in cancer: a review of the literature

Galectin-3 is a β-galactoside-binding animal lectin that contains carbohydrate-recognition domains and displays multiple related functions. It has important roles in diverse biological events, such as embryogenesis, growth, cell adhesion, proliferation, differantiation, cell-cycle progression, apoptosis, mRNA splicing, and regulation of the immune system. Galectin-3 is expressed in various cells and tissues, such as activated macrophages, eosinophils, neutrophils, mast cells, epithelium of the gastrointestinal and respiratory tracts, kidneys and some sensory neurons, and is also involved in tumorigenesis, angiogenesis, and tumor metastasis. In this review of the literature, immunohistochemical Galectin-3 expression is investigated in numerous tumors and disorders of various organ systems.     

Expression of endogenous galectin-1 and galectin-3 in intrahepatic cholangiocarcinoma

Galectins, a family of beta-galactoside-binding animal lectins, might be involved in tumor progression. In this study, the expression patterns of galectin-1 and -3 were examined immunohistochemically in intrahepatic cholangiocarcinoma (ICC), with emphasis on its development and progression as well as its histopathologic features, by use of samples of normal intrahepatic bile duct (n = 20), biliary epithelial dysplasia (n = 15), ICC (n = 40), and a cholangiocarcinoma cell line, CCKS1. In normal intrahepatic bile ducts, galectin-3 was constitutively but weakly expressed, whereas galectin-1 was not expressed. In hepatolithiasis, biliary epithelial dysplasia was strongly positive for galectin-3 but negative for galectin-1. Galectin-3 was frequently and strongly expressed in the cytoplasm of well-differentiated ICCs, and its expression was significantly decreased and less intense or even absent in poorly differentiated ICCs. Galectin-1 was expressed in carcinoma cells in ICC, and its incidence and extent were correlated with histologic dedifferentiation of ICC. Proliferative cell nuclear antigen (PCNA) labeling index (LI) was higher in ICC cases positive for galectin-1 than in those that were negative. Galectin-1 was strongly expressed in cancerous stroma of ICC, and this stromal expression was related to histologic dedifferentiation of ICC. In the carcinoma cell line CCKS1, galectin-1 and -3 were expressed in the cytoplasm of carcinoma cells, and galectin-1 was additionally detected in the culture medium. These results suggest that galectin-1 was newly expressed on carcinoma cells of ICC, and its overexpression seems to be associated with neoplastic progression and proliferative activities, and the expression of galectin-1 in cancerous stroma may also be related to the progression of ICC. Galectin-3 expression in epithelial cells is up-regulated in the preneoplastic and early neoplastic stages of ICC, although galectin-3 tends to disappear at later stages of ICC. HUM PATHOL 32:302-310.     

Immunohistochemical Expression of the Intracellular Component of Galectin-8 in Squamous Cell Metaplasiaof the Bronchial Epitheliumin Neoplastic and Benign Processes

Specified galectins are known to play a role in regulating cell proliferation, differentiation, adhesion and migration. Po66, a mouse IgG1 monoclonal antibody produced by immunization against squamous cell cancer, reacts against a carbohydrate-binding protein (Po66-CBP), recently shown to be a member of the galectin family with a strong homology with galectin-8 (PCTA-1), identified as a human tumor-associated antigen.

We studied Po66 in squamous metaplasia of the bronchi in order to determine whether it could be specifically involved in neoplastic conditions and if so, if it would be helpful in distinguishing metaplasia at risk of cancer.

Twenty-eight formalin-fixed, paraffin-embedded archival tissues of 17 metaplasias with SCC, 3 metaplasia with distant neoplastic disease and 8 metaplasias with an inflammatory process, were immunostained using a streptavidin biotin peroxydase method.

The squamous metaplasias were positively stained in non-neoplastic disease as well as in neoplastic processes. Expression was also observed in stromal and normal cells.

Po66-CBP was not associated with a pre-neoplastic character. We discussed the expression of this intra-cellular component of galectin-8 according to the functions of galectins in cellular differentiation, host reaction against tumor, and inflammation.     

Increased expression of galectin-1 in carcinoma-associated stroma predicts poor outcome in prostate carcinoma patients

Galectin-1, a member of the beta-galactoside-binding galectin family, is a pleiotropic dimeric protein participating in a variety of normal and pathological processes, including cancer progression. Modulation of the interactions with the basement membrane glycoprotein laminin and induction of apoptosis in activated T lymphocytes are well-known functions of this galectin. In this study, the expression of galectin-1 was examined in 148 human primary prostate carcinoma samples. Immunohistochemical staining of paraffin sections of prostate tissues revealed that galectin-1 was not detected in normal, PIN (prostatic intraepithelial neoplasia) or carcinoma cells, but accumulated in the stroma and associated fibroblasts. Galectin-1 expression was significantly increased in the tumour-associated stroma compared with the non-neoplastic gland-associated stroma in 21.3% of the cases (Mantel-Haenszel test, p=0.001; Wilcoxon signed rank test, p<0.0001). Increased galectin-1 expression in the cancer-associated stroma compared to the normal gland-associated stroma (p=0.03) was identified by multivariate analysis as a strong independent predictor of prostate-specific antigen (PSA) recurrence, just after the pathological stage (p<0.0001). The association between accumulation of galectin-1 in the stroma of the malignant tissue and aggressiveness of the tumour adds weight to the body of evidence that identifies a role for galectin-1 in the acquisition of the invasive phenotype. In addition to modulating cancer cell interactions with laminin, galectin-1 accumulated around the cancer cells may act as an immunological shield by inducing activated T-cell apoptosis. This exciting hypothesis warrants further investigation.     

The role of galectins in virus infection - A systemic literature review

BackgroundGalectins are β-Galactose binding lectins expressed in numerous cells and play multiple roles in various physiological and cellular functions. However, few information is available regarding the role of galectins in virus infections. Here, we conducted a systemic literature review to analyze the role of galectins in human virus infection.MethodsThis study uses a systematic method to identify and select eligible articles according to the PRISMA guidelines. References were selected from PubMed, Web of Science and Google Scholar database covering publication dated from August 1995 to December 2018.ResultsResults indicate that galectins play multiple roles in regulation of virus infections. Galectin-1 (Gal-1), galectin-3 (Gal-3), galectin-8 (Gal-8), and galectin-9 (Gal-9) were found as the most predominant galectins reported to participate in virus infection. The regulatory function of galectins occurs by extracellularly binding to viral glycosylated envelope proteins, interacting with ligands or receptors on immune cells, or acting intracellularly with viral or cellular components in the cytoplasm. Several galectins express either positive or negative regulatory role, while some had dual regulatory capabilities on virus propagation based on the conditions and their localization. However, limited information about the endogenous function of galectins were found. Therefore, the endogenous effects of galectins in host-virus regulation remains valuable to investigate.ConclusionsThis study offers information regarding the various roles galectins shown in viral infection and suggest that galectins can potentially be used as viral therapeutic targets or antagonists.