Effect of 5-azacytidine and galectin-1 on growth and differentiation of the human b lymphoma cell line bl36

Promoter methylation might shift the balance of Galectin-3 & 12 expression in de novo adult acute myeloid leukemia patients

Acute myeloid leukemia (AML) was reported as the most common type of leukemia among adults. Galectins constitute a family of galactose-binding proteins reported to play a critical role in many malignancies including AML. Galectin-3 and -12 are members of the mammalian galectin family. To understand the contribution of galectin-3 and -12 promoter methylation to their expression, we performed bisulfite methylation-specific (MSP)-PCR and bisulfite genomic sequencing (BGS) of primary leukemic cells in patients with de novo AML before receiving any therapy. Here, we show a significant loss of LGALS12 gene expression in association with promoter methylation. The lowest degree of expression was found in the methylated (M) group while the highest degree was in the unmethylated (U) group and the partially methylated (P) group expression lies in between. This was not the case with galectin-3 in our cohort unless the CpG sites analyzed were outside the frame of the studied fragment. We were also able to identify four CpG sites (CpG number 1, 5, 7& 8) in the promoter region of galectin-12; these sites must be unmethylated so that expression can be induced. As far as the authors know, these findings were not previously concluded in earlier studies.

The Emerging Role of Galectins and O-GlcNAc Homeostasis in Processes of Cellular Differentiation

Galectins are a family of soluble β-galactoside-binding proteins with diverse glycan-dependent and glycan-independent functions outside and inside the cell. Human cells express twelve out of sixteen recognized mammalian galectin genes and their expression profiles are very different between cell types and tissues. In this review, we summarize the current knowledge on the changes in the expression of individual galectins at mRNA and protein levels in different types of differentiating cells and the effects of recombinant galectins on cellular differentiation. A new model of galectin regulation is proposed considering the change in O-GlcNAc homeostasis between progenitor/stem cells and mature differentiated cells. The recognition of galectins as regulatory factors controlling cell differentiation and self-renewal is essential for developmental and cancer biology to develop innovative strategies for prevention and targeted treatment of proliferative diseases, tissue regeneration, and stem-cell therapy.

Analyzing epigenetic control of galectin expression indicates silencing of galectin-12 by promoter methylation in colorectal cancer

Galectins, a class of lectins with specificity for ß-galactoside containing glycoconjugates, modulate several cellular processes that are involved in the control of normal cell growth, differentiation, cell-cell, and cell matrix interactions. Pathological alterations of the galectin expression pattern have been implicated in the development and progression of cancer. We therefore analyzed epigenetic mechanisms for control of galectin expression in 9 colorectal cancer (CRC) cell lines. Our data demonstrate that expression of galectins-1, -2, -7, -8, and -9 can be regulated by histone acetylation in CRC cell lines. In addition, the same set of galectins was also found to be modulated by DNA methylation. Of particular note, galectin-12 is silenced in all tested CRC cell lines but known to be re-expressed upon butyrate-induced differentiation and present in normal colonic mucosa. Loss of galectin-12 expression in undifferentiated CRC cells is associated with promoter hypermethylation and for the first time we provide detailed methylation analysis of the promoter region. In CRC tumor tissue, galectin-12 expression was downregulated in 66% of CRC tissue specimens as compared to adjacent normal tissue hinting to a possible tumor-suppressing function in CRC. © 2017 IUBMB Life, 69(12):962-970, 2017.

The Differential Expression of Galectin-1 and Galectin-3 in Normal Lymphoid Tissue and Non-Hodgkin's and Hodgkin's Lymphomas

The WHO classification of lymphomas was established on the basis of clinical, morphological, immunohistochemical and genetic criteria. However, each entity displays its own spectrum of clinical aggressiveness. Treatment success varies widely and is not predictable. Since galectins are involved in oncogenesis and the physiology of immune cells, we investigated whether galectin-1 and galectin-3 immunohistochemical expression could differ in 25 normal lymphoid tissues, 42 non-Hodgkin's and 14 Hodgkin's lymphomas. Immunohistochemical galectin expression was submitted to semi-quantitative and quantitative (computer-assisted microscopy) evaluations. This study is completed by an analysis (by means of quantitative RT-PCR) of galectin-3 mRNA expression in 3 normal lymph nodes, 3 follicular lymphomas (FLs) and 3 diffuse large B-cell lymphomas (DLBCLs). The data show that in normal lymphoid tissue, lymphocytes do not express galectin-1 and rarely express galectin-3. In contrast, galectin-3 was expressed in 8 of the 16 DLBCL cases and in 1 of the 8 FL cases. Furthermore, galectin-3 mRNA was expressed 3-times more in the DLBCLs than in the FLs. While the blood vessel walls of the lymphomas expressed galectin-1, the vessel walls of normal lymphoid tissues did not. This expression of galectin-1 in blood vessel walls was correlated with vascular density. The present study thus shows that DLBCL can be distinguished from normal lymphoid tissue and other lymphomas on the basis of galectin-3 expression.

CSBF/C10orf99, a novel potential cytokine, inhibits colon cancer cell growth through inducing G1 arrest

Cytokines are soluble proteins that exert their functions by binding specific receptors. Many cytokines play essential roles in carcinogenesis and have been developed for the treatment of cancer. In this study, we identified a novel potential cytokine using immunogenomics designated colon-derived SUSD2 binding factor (CSBF), also known as chromosome 10 open reading frame 99 (C10orf99). CSBF/C10orf99 is a classical secreted protein with predicted molecular mass of 6.5 kDa, and a functional ligand of Sushi Domain Containing 2 (SUSD2). CSBF/C10orf99 has the highest expression level in colon tissue. Both CSBF/C10orf99 and SUSD2 are down-regulated in colon cancer tissues and cell lines with different regulation mechanisms. CSBF/C10orf99 interacts with SUSD2 to inhibit colon cancer cell growth and induce G1 cell cycle arrest by down-regulating cyclin D and cyclin-dependent kinase 6 (CDK6). CSBF/C10orf99 displays a bell-shaped activity curve with the optimal effect at ~10 ng/ml. Its growth inhibitory effects can be blocked by sSUSD2-Fc soluble protein. Our results suggest that CSBF/C10orf99 is a novel potential cytokine with tumor suppressor functions.

Intracellular galectins in cancer cells: potential new targets for therapy (Review)

Dysregulation of galectin expression is frequently observed in cancer tissues. Such an abnormal expression pattern often correlates with aggressiveness and relapse in many types of cancer. Because galectins have the ability to modulate functions that are important for cell survival, migration and metastasis, they also represent attractive targets for cancer therapy. This has been well-exploited for extracellular galectins, which bind glycoconjugates expressed on the surface of cancer cells. Although the existence of intracellular functions of galectins has been known for many years, an increasing number of studies indicate that these proteins can also alter tumor progression through their interaction with intracellular ligands. In fact, in some instances, the interactions of galectins with their intracellular ligands seem to occur independently of their carbohydrate recognition domain. Such findings call for a change in the basic assumptions, or paradigms, concerning the activity of galectins in cancer and may force us to revisit our strategies to develop galectin antagonists for the treatment of cancer.

Proteomics in hematologic malignancies

Basic science research in hematology has been determining the functions of gene products using classical approaches that typically involve studying one or a few genes at a time. Proteomics, defined as the study of protein properties on a large scale, provides tools to globally analyze malignant hematologic cells. A major challenge in cancer therapy is the identification of drugs that kill tumor cells while preserving normal cells. Differential display via proteomics enables analysis of direct as well as side-effects of drugs at a molecular level. Proteomics also allows a better understanding of cell signaling pathways involved during apoptosis in hematologic cells. Storing the information in a 2D electrophoresis database enhances the efficiency of proteome research on malignant cells. Finally, the work needed to be carried out on proteomic analysis prior to routine clinical adoption is discussed, and the necessity for multi-institutional collaborations is emphasized.

Epigenetic drug 5-azacytidine impairs proliferation of rat limb buds in an organotypic model-system in vitro

AIM

To establish an organotypic in vitro model of limb bud development to verify whether epigenetic drug and teratogen 5-azacytidine (5azaC) has an effect on limb buds independent of its effects on the placenta.

METHODS

Fischer strain rat fore- and hindlimb buds were microsurgically isolated from 13 days old embryos and cultivated in vitro for two weeks at the air-liquid interface in Eagle's minimum essential medium (MEM) with 50% rat serum. 30 μmol of 5azaC was added to the fresh medium. Overall growth was measured by an ocular micrometer. Routine histology, immunohistochemical detection of the proliferating cell nuclear antigen (PCNA), and stereological quantification of PCNA expression were performed.

RESULTS

At four time points, significantly lower overall growth was detected for fore- and hindlimb bud explants cultivated with 5azaC in comparison to controls. After the culture period, numerical density of the PCNA signal for both types of limb buds was lower than for controls (P<0.001). Limb buds were initially covered by immature epithelium and contained mesenchyme, myotubes, single hemangioblasts, hemangioblast aggregates, blood islands, and capillaries. Regardless of the treatment, cartilage and epidermis differentiated, but cells and structures typical for vasculogenesis disappeared.

CONCLUSION

Our findings, obtained outside of the maternal organism, stress the importance of compromised cell proliferation for 5azaC impact on limb buds. This investigation points to the necessity to establish alternatives to in vivo research on animals using teratogenic agents.

Methylation of P16 in exhaled breath condensate for diagnosis of non-small cell lung cancer

BACKGROUND

Non-small cell lung cancer is the most frequently cause of cancer-related death in the world. To explore the technical feasibility, we detected aberrant promoter methylation of P16 in exhaled breath condensate which was a new, non-invasive tool for diagnosis and screening program of NSCLC.

METHODS

We analyzed aberrant promoter methylation of P16 in 180 samples from 60 individuals, including 30 NSCLC patients (cancer tissues, adjacent normal lung tissues, blood plasma, and EBC), and 30 healthy controls (blood plasma and EBC) by fluorescent quantitative methylation-specific polymerase chain reaction (F-MSP).

RESULTS

The positive rate of aberrant promoter methylation of P16 was 26 of 30 (86.66%) in tumor tissues, 15 of 30 (50%) in blood plasma, and 12 of 30 (40%) in EBC, we have not observed the positive methylation of P16 in the adjacent normal lung tissues, or in EBC or blood plasma from the healthy control group.

CONCLUSION

We found that detected promoter methylation of P16 in EBC was feasibility, it should be an useful biomarker for diagnosis of NSCLC, it have potential prospect that detected the gene molecular in EBC because of noninvasive, specificity, convenient and repeatable.

Context-dependent multifunctionality of galectin-1: a challenge for defining the lectin as therapeutic target

INTRODUCTION

One route of translating the information encoded in the glycan chains of cellular glycoconjugates into physiological effects is via receptor (lectin) binding. A family of endogenous lectins, sharing folding, a distinct sequence signature and affinity for β-galactosides (thus termed galectins), does so effectively in a context-dependent manner.

AREAS COVERED

An overview is given on the multifunctional nature of galectins, with emphasis on galectin-1. The broad range of functions includes vital processes such as adhesion via glycan bridging, glycoconjugate transport or triggering signaling relevant, for example, for growth regulation. Besides distinct glycoconjugates, this lectin can also interact with certain proteins so that it can target counterreceptors at all sites of location, that is, in the cytoplasm and/or nucleus, at both sides of the membrane or extracellularly. Approaches to strategically exploit galectin activities with therapeutic intentions are outlined.

EXPERT OPINION

The wide versatility of sugar coding and the multifunctionality of galectin-1 explain why considering to turn the protein into a therapeutic target is an ambitious aim. Natural pathways shaped by physiologic master regulators (e.g., the tumor suppressor p16(INK4a)) are suggested to teach inspiring lessons as to how the lectin might be recruited to clinical service.

Satellite 2 demethylation induced by 5-azacytidine is associated with missegregation of chromosomes 1 and 16 in human somatic cells

Satellite sequences are an important part of the pericentromeric regions in mammalian genomes; they play a relevant role in chromosome stability and DNA hypomethylation of these sequences has been reported in ICF syndrome and in some cancers that are closely associated with chromosomal abnormalities. Epigenetic modifications of satellite sequences and their consequences have not been extensively studied in human cells. In the present work, we evaluated satellite 2 methylation patterns in human lymphocytes exposed to 5-azacytidine (5-azaC) and assessed the relationship between these patterns and chromosome missegregation. Human lymphocytes were exposed to 10μM 5-azaC for 24, 48, and 72h. Segregation errors were evaluated in binucleate cells using FISH against pericentromeric regions of chromosomes 1, 9, and 16. DNA methylation patterns were evaluated by immunodetection, and by bisulfite plus urea conversion and sequencing. We have identified that 5-azaC induced missegregation of chromosomes 1 and 16, which have highly methylated satellite 2, after 72h of exposure. Chromosome methylation patterns showed a notable decrease in pericentromeric methylation. Bisulfite conversion and sequencing analysis demonstrated demethylation of satellite 2 associated to 5-azaC exposure, principally after 72h of treatment. This change occurred in a non-specific pattern. Our study demonstrates an association between loss of satellite 2 DNA methylation and chromosome loss in human lymphocytes.

The glycan-binding protein galectin-1 controls survival of epithelial cells along the crypt-villus axis of small intestine

Intestinal epithelial cells serve as mechanical barriers and active components of the mucosal immune system. These cells migrate from the crypt to the tip of the villus, where different stimuli can differentially affect their survival. Here we investigated, using in vitro and in vivo strategies, the role of galectin-1 (Gal-1), an evolutionarily conserved glycan-binding protein, in modulating the survival of human and mouse enterocytes. Both Gal-1 and its specific glyco-receptors were broadly expressed in small bowel enterocytes. Exogenous Gal-1 reduced the viability of enterocytes through apoptotic mechanisms involving activation of both caspase and mitochondrial pathways. Consistent with these findings, apoptotic cells were mainly detected at the tip of the villi, following administration of Gal-1. Moreover, Gal-1-deficient (Lgals1^−/−) mice showed longer villi compared with their wild-type counterparts in vivo. In an experimental model of starvation, fasted wild-type mice displayed reduced villi and lower intestinal weight compared with Lgals1^−/− mutant mice, an effect reflected by changes in the frequency of enterocyte apoptosis. Of note, human small bowel enterocytes were also prone to this pro-apoptotic effect. Thus, Gal-1 is broadly expressed in mucosal tissue and influences the viability of human and mouse enterocytes, an effect which might influence the migration of these cells from the crypt, the integrity of the villus and the epithelial barrier function.

Increased galectin-7 gene expression in lymphoma cells is under the control of DNA methylation

Recent studies have reported that elevated levels of galectin-7 in different types of cancer. The mechanisms underlying its abnormal regulation in cancer cells remain, however, unknown. Here, we have examined the relationship between galectin-7 and p53, a gene previously associated with upregulation of galectin-7. While RNA and protein analyses revealed a consistent and irreversible upregulation of galectin-7 throughout progression of lymphoma, no correlation with p53 was found. In fact, most of the lymphoma cell lines expressing high levels of galectin-7 did not express any detectable level of p53, although expressed p21(Waf1/Cip1) gene following doxorubicin treatment, indicating that p53 was functional in these cells. Methylation-specific polymerase chain reaction (MS-PCR) analyses rather suggested that galectin-7 expression was associated with changes in DNA methylation. This conclusion was supported by data using demethylating agent 5-aza-dC. Furthermore, disruption of the DNA methylases dnmt1 and dnmt3a induced galectin-7. Collectively, our data suggest that abnormal expression of galectin-7 in lymphoma cells is not dependent on p53, but is rather associated with DNA hypomethylation.

Tumor suppressor p16INK4a--modulator of glycomic profile and galectin-1 expression to increase susceptibility to carbohydrate-dependent induction of anoikis in pancreatic carcinoma cells

Expression of the tumor suppressor p16(INK4a) after stable transfection can restore the susceptibility of epithelial tumor cells to anoikis. This property is linked to increases in the expression and cell-surface presence of the fibronectin receptor. Considering its glycan chains as pivotal signals, we assumed an effect of p16(INK4a) on glycosylation. To test this hypothesis for human Capan-1 pancreatic carcinoma cells, we combined microarray for selected glycosyltransferase genes with 2D chromatographic glycan profiling and plant lectin binding. Major differences between p16-positive and control cells were detected. They concerned expression of beta1,4-galactosyltransferases (down-regulation of beta1,4-galactosyltransferases-I/V and up-regulation of beta1,4-galactosyltransferase-IV) as well as decreased alpha2,3-sialylation of O-glycans and alpha2,6-sialylation of N-glycans. The changes are compatible with increased beta(1)-integrin maturation, subunit assembly and binding activity of the alpha(5)beta(1)-integrin. Of further functional relevance in line with our hypothesis, we revealed differential reactivity towards endogenous lectins, especially galectin-1. As a result of reduced sialylation, the cells' capacity to bind galectin-1 was enhanced. In parallel, the level of transcription of the galectin-1 gene increased conspicuously in p16(INK4a)-positive cells, and even figured prominently in a microarray on 1996 tumor-associated genes and in proteomic analysis. The cells therefore gain optimal responsiveness. The correlation between genetically modulated galectin-1 levels and anoikis rates in engineered transfectants inferred functional significance. To connect these findings to the fibronectin receptor, galectin-1 was shown to be co-immunoprecipitated. We conclude that p16(INK4a) orchestrates distinct aspects of glycosylation that are relevant for integrin maturation and reactivity to an endogenous effector as well as the effector's expression. This mechanism establishes a new aspect of p16(INK4a) functionality.

Galectin-1: a small protein with major functions

Galectins are a family of carbohydrate-binding proteins with an affinity for beta-galactosides. Galectin-1 (Gal-1) is differentially expressed by various normal and pathological tissues and appears to be functionally polyvalent, with a wide range of biological activity. The intracellular and extracellular activity of Gal-1 has been described. Evidence points to Gal-1 and its ligands as one of the master regulators of such immune responses as T-cell homeostasis and survival, T-cell immune disorders, inflammation and allergies as well as host-pathogen interactions. Gal-1 expression or overexpression in tumors and/or the tissue surrounding them must be considered as a sign of the malignant tumor progression that is often related to the long-range dissemination of tumoral cells (metastasis), to their dissemination into the surrounding normal tissue, and to tumor immune-escape. Gal-1 in its oxidized form plays a number of important roles in the regeneration of the central nervous system after injury. The targeted overexpression (or delivery) of Gal-1 should be considered as a method of choice for the treatment of some kinds of inflammation-related diseases, neurodegenerative pathologies and muscular dystrophies. In contrast, the targeted inhibition of Gal-1 expression is what should be developed for therapeutic applications against cancer progression. Gal-1 is thus a promising molecular target for the development of new and original therapeutic tools.

Proteome analysis in the study of lymphoma cells

This review provides an overview on recent studies in the field of proteome analysis of lymphoma cells, and highlights the potentials of such studies for a better knowledge of drug effects at the molecular level. After giving general information on the field of proteome analysis of lymphoma cells, some characteristics of the strategies used during this analysis are pointed out, such as cell extraction strategies and affinity captures. Therefore, the issue of proteome analysis of lymphoma cells content will be covered with respect to those protein extracts that can be prepared in saline solutions, such as cytoplasm proteins, or that are associated with the cell membranes. The question of which kinds of information have been retrieved from lymphoma-cell proteomics is discussed on the basis of several examples-lymphoma cell-mapping studies and constitution of protein databases, and comparative proteome analysis studies of the modifications that result from a drug treatment.

Proteomic Study of Galectin-1 Expression in Human Mesenchymal Stem Cells

Bone marrow-derived mesenchymal stem cells (MSCs) are known to interact with hematopoietic stem cells (HSCs) and immune cells, and are of potential interest to be used as therapeutic agents for enhancing allogenic hematopoietic engraftment and preventing graft-versus-host disease (GVHD). Galectin 1 (Gal1) belongs to a family of structurally related molecules expressed in many vertebrate tissues that exert their functions both by binding to glycoconjugates, and by interaction with protein partners. In this work using a proteomic approach, we looked for the presence and the localization of Gal1 in short- and long-term culture of human (h) hMSC. We first determined, that Gal1 is one of the major proteins expressed in hMSC. We futher demonstrated that its expression is maintained when hMSC are expanded through a subculturing process up to five passages. Moreover, Gal1 is secreted and found at the cell surface of MSC, participating in extra cellular matrix (ECM)-cell interactions. Given the immunomodulatory properties of Gal1, its potential involvement in immunological functions of hMSC could be suggested.

Galectin genes: regulation of expression

In this review we have summarized the more recent studies on the expression of mammalian galectins. One interesting observation that can be made is that in most of microarrays and/or differential display analysis performed in recent years one or more galectins have been picked up. From a critical evaluation of the pertinent studies the main conclusion that can be drawn is that, although it is not yet clear whether the 14 galectins identified so far have functions in common, a striking common feature of all galectins is the strong modulation of their expression during development, differentiation stages and under different physiological or pathological conditions. This suggests that the expression of different galectins is finely tuned and possibly coordinated. In spite of these observations it is rather unexpected that very few studies have been performed on the molecular mechanisms governing the activity of galectin genes.

Proteomic signature corresponding to alpha fetoprotein expression in liver cancer cells

Alpha fetoprotein (AFP) has been implicated in the development of hepatocellular carcinoma and is considered to be a diagnostic and prognostic tumor marker. Because elevated expression of AFP is associated with many characteristics of hepatocellular carcinoma tissues, we hypothesized that multiple proteins may function in a coordinated manner with AFP. To identify such proteins, we performed global protein expression analysis, namely a proteomic study. The protein expression profiles of 9 AFP-producing liver cancer cell lines (JHH-5, HuH-1, PLC/PRL/5, Hep3B, HT-17, JHH-7, HuH-7, HepG2, Li-7) and 7 nonproducing liver cancer cell lines (HLE, JHH-6, Sk-Hep-1, JHH-4, HLF, RBE, SSP-25) were generated by fluorescence 2-dimensional difference gel electrophoresis. In fluorescence 2-dimensional difference gel electrophoresis, proteins are labeled with fluorescent dyes before electrophoresis for more accurate quantitative expression analysis. We identified 11 protein spots that distinguished AFP-producing cell lines from nonproducing cell lines by multivariate studies. The spots showed consistent alterations in amount in AFP-producing cell lines (6 up-regulated and 5 down-regulated). An additional 5 liver cancer cell lines (KIM-1, KYN-2, KYN-3, PH5-CH, PH5-T) also were correctly grouped with respect to their AFP production on the basis of the intensity of the 11 protein spots. The proteins corresponding to the 11 selected spots were identified by mass spectrometry and were categorized into 4 groups based on their known role in apoptosis, glucose metabolism, cytoskeletal organization, or translation. In conclusion, we found a novel association of AFP with other proteins. Their interaction should provide insight into the biology of AFP-producing hepatocellular carcinoma cells.