Mariana P. Stelling

Extracellular Galectin-3 in Tumor Progression and Metastasis

Galectin-3, the only chimera galectin found in vertebrates, is one of the best-studied galectins. It is expressed in several cell types and is involved in a broad range of physiological and pathological processes, such as cell adhesion, cell activation and chemoattraction, cell cycle, apoptosis, and cell growth and differentiation. However, this molecule raises special interest due to its role in regulating cancer cell activities. Galectin-3 has high affinity for β-1,6-N-acetylglucosamine branched glycans, which are formed by the action of the β1,6-N-acetylglucosaminyltransferase V (Mgat5). Mgat5-related changes in protein/lipid glycosylation on cell surface lead to alterations in the clustering of membrane proteins through lattice formation, resulting in functional advantages for tumor cells. Galectin-3 presence enhances migration and/or invasion of many tumors. Galectin-3-dependent clustering of integrins promotes ligand-induced integrin activation, leading to cell motility. Galectin-3 binding to mucin-1 increases transendothelial invasion, decreasing metastasis-free survival in an experimental metastasis model. Galectin-3 also affects endothelial cell behavior by regulating capillary tube formation. This lectin is found in the tumor stroma, suggesting a role for microenvironmental galectin-3 in tumor progression. Galectin-3 also seems to be involved in the recruitment of tumor-associated macrophages, possibly contributing to angiogenesis and tumor growth. This lectin can be a relevant factor in turning bone marrow in a sanctuary for leukemia cells, favoring resistance to therapy. Finally, galectin-3 seems to play a relevant role in orchestrating distinct cell events in tumor microenvironment and for this reason, it can be considered a target in tumor therapies. In conclusion, this review aims to describe the processes of tumor progression and metastasis involving extracellular galectin-3 and its expression and regulation.

Valproate reverts zinc and potassium imbalance in schizophrenia-derived reprogrammed cells

Schizophrenia has been considered a devastating clinical syndrome rather than a single disease. Nevertheless, the mechanisms behind the onset of schizophrenia have been only partially elucidated. Several studies propose that levels of trace elements are abnormal in schizophrenia; however, conflicting data generated from different biological sources prevent conclusions being drawn. In this work, we used synchrotron radiation X-ray microfluorescence spectroscopy to compare trace element levels in neural progenitor cells (NPCs) derived from two clones of induced pluripotent stem cell lines of a clozapine-resistant schizophrenic patient and two controls. Our data reveal the presence of elevated levels of potassium and zinc in schizophrenic NPCs. Neural cells treated with valproate, an adjunctive medication for schizophrenia, brought potassium and zinc content back to control levels. These results expand the understanding of atomic element imbalance related to schizophrenia and may provide novel insights for the screening of drugs to treat mental disorders.

Heparan sulfates from arteries and veins differ in their antithrombin-mediated anticoagulant activity.

Because he moved to another city a few weeks after hospital discharge, a repeat TG assay was not possible. A telephone interview conducted 6 months later revealed that he did not experience any clinically obvious clotting abnormality again. In our patient, treatment with IVIG led to a normalization of hemostasis as confirmed by the TG assay, the disappearance of FV inhibitor, and the rise in FV activity. IVIGwas given on the basis of its reported efficacy in patients with acquired hemophilia A.However, a spontaneous recovery cannot be ruled out withcertainty.Theamountof thrombingenerated, the lagphase and the time to thrombin peak are influenced by FV, as FV is part of every step in the process of TG [4]. Platelet FV rather than plasma FV plays a significant role in the amplification phase of coagulation. FV inhibitor leads to an impaired initiation phase, and this in turn results in impaired platelet activation. On the other hand, FV on the surface of activated platelets becomes neutraliszed by FV inhibitor, which leads to a reduction in prothrombinase activity and thrombin burst. The amount of FV needed to produce an adequate thrombin burst is still unclear. In our patient, minimal changes in FV activity from 7.4% to 8.6% led to a considerable increase in thrombin formation. Higher concentrations of FV did not result in any further increase in ETP, but did result in further reductions in the lag phase and the time to peak. Al Dieri et al. [5] observed no severe impairment in ETP at FV levels of 2% in patients with congenital FV deficiency. However, they used much higher TF concentrations (15 pM) in their assay. Therefore, their data are hardly comparable to ours. Furthermore, a measurable amount of the coagulation factor in the presence of an acquired autologous inhibitor may not necessarily correlate with its hemostatic function. Studies in patients with acquired autoantibody hemophilia A have shown that the inactivation has a type II pattern, with some residual FVIII activity being identifiable even after incubation at high concentrations of antibody. The presence of the inhibitor rather than the measurable coagulation factor activity is thus important in assessing the hemostatic state. In conclusion, the TG assay could be useful for monitoring hemostatic changes in patients with FV deficiency due to an inhibitor. However, there are issues of standardization to be dealt with. Clinical correlation with TG cut-off values is also lacking. These issues have to be addressed before the assay can be used in clinical routine practice.

Synchrotron Radiation X-Ray Microfluorescence Reveals Polarized Distribution of Atomic Elements during Differentiation of Pluripotent Stem Cells

The mechanisms underlying pluripotency and differentiation in embryonic and reprogrammed stem cells are unclear. In this work, we characterized the pluripotent state towards neural differentiated state through analysis of trace elements distribution using the Synchrotron Radiation X-ray Fluorescence Spectroscopy. Naive and neural-stimulated embryoid bodies (EB) derived from embryonic and induced pluripotent stem (ES and iPS) cells were irradiated with a spatial resolution of 20 µm to make elemental maps and qualitative chemical analyses. Results show that these embryo-like aggregates exhibit self-organization at the atomic level. Metallic elements content rises and consistent elemental polarization pattern of P and S in both mouse and human pluripotent stem cells were observed, indicating that neural differentiation and elemental polarization are strongly correlated.

Heparanase expression and localization in different types of human lung cancer.

BACKGROUND Heparanase is the only known mammalian glycosidase capable of cleaving heparan sulfate chains. The expression of this enzyme has been associated with tumor development because of its ability to degrade extracellular matrix and promote cell invasion. METHODS We analyzed heparanase expression in lung cancer samples to understand lung tumor progression and malignancy. Of the samples from 37 patients, there were 14 adenocarcinomas, 13 squamous cell carcinomas, 5 large cell carcinomas, and 5 small cell carcinomas. Immunohistochemistry was performed to ascertain the expression and localization of heparanase. RESULTS All of the tumor types expressed heparanase, which was predominantly localized within the cytoplasm and nucleus. Significant enzyme expression was also observed in cells within the tumor microenvironment, such as fibroblasts, epithelial cells, and inflammatory cells. Adenocarcinomas exhibited the strongest heparanase staining intensity and the most widespread heparanase distribution. Squamous cell carcinomas, large cell carcinomas, and small cell carcinomas had a similar subcellular distribution of heparanase to adenocarcinomas but the distribution was less widespread. Heparanase expression tended to correlate with tumor node metastasis (TNM) staging in non-small cell lung carcinoma. CONCLUSION In this study, we showed that heparanase was localized to the cytoplasm and nucleus of tumor cells and to cells within the microenvironment in different types of lung cancer. This enzyme exhibited a differential distribution based on the type of lung tumor. General significance Elucidating the heparanase expression patterns in different types of lung cancer increased our understanding of the crucial role of heparanase in lung cancer biology. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

Trace elements during primordial plexiform network formation in human cerebral organoids

Systematic studies of micronutrients during brain formation are hindered by restrictions to animal models and adult post-mortem tissues. Recently, advances in stem cell biology have enabled recapitulation of the early stages of human telencephalon development in vitro. In the present work, we analyzed cerebral organoids derived from human pluripotent stem cells by synchrotron radiation X-ray fluorescence in order to measure biologically valuable micronutrients incorporated and distributed into the exogenously developing brain. Our findings indicate that elemental inclusion in organoids is consistent with human brain tissue and involves P, S, K, Ca, Fe and Zn. Occurrence of different concentration gradients also suggests active regulation of elemental transmembrane transport. Finally, the analysis of pairs of elements shows interesting elemental interaction patterns that change from 30 to 45 days of development, suggesting short- or long-term associations, such as storage in similar compartments or relevance for time-dependent biological processes. These findings shed light on which trace elements are important during human brain development and will support studies aimed to unravel the consequences of disrupted metal homeostasis for neurodevelopmental diseases, including those manifested in adulthood.

Neural induced embryoid bodies present high levels of metals detected by x-ray microfluorescence

Molecular mechanisms driving neural differentiation in human embryonic stem cells are not completely elucidated, specially, the role of atomic elements within this process. In this work, we described the distribution of trace elements in those stem cells growing as embryoid bodies by using synchrotron radiation X-ray microfluorescence (SR-XRF). Naive and neural induced embryoid bodies derived from embryonic stem cells were irradiated with a spatial resolution of 20 μm to make elemental maps and qualitative chemical analyses. We consistently detected metallic elements content raise on neural induced embryoid bodies, mimicking characteristic brain development. The use of SR-XRF reveals that human embryoid bodies exhibit self-organization at the atomic level, which is enhanced during neurogenesis triggered in vitro.

17-P006 Human embryonic stem cells cultured onto MEF-derived organized extracellular matrix are pluripotent and form embryoid bodies

While adult neurogenesis in mammals is mainly restricted to two telencephalic zones, in teleost fishes, neurogenesis has been observed in many brain areas. Hence, the medaka (Oryzias latipes) represents an excellent model to study neural stem cells (NSCs). In order to detect NSCs, we have relied on the fact that adult stem cells divide more slowly than quickly amplifying progenitor cells. By using two different thymidine analogs and performing long pulses separated by a long period of time, we have managed to identify cells that are double-labelled in the medaka brain. These slow-proliferating cells are likely to be NSCs. We have looked more precisely at neurogenesis in a cortical structure of the dorsal midbrain, the optic tectum. Cell proliferation occurs at its margin throughout life. With the thymidine analog labeling, we have identified some slow-dividing cells, in the tectum, forming a narrow line at the very periphery of the proliferative zone. This topographic organization allowed us to perform an insitu hybridization screen on medaka embryos and find a dozen of genes whose expression corresponds to this thin line of putative NSCs. By analyzing the functions of these genes, we hope to identify essential genes for adult NSC and embryonic NSC biology. We should be able to bring cues on the conserved features between fish and mammal stem cells and examine whether neurogenesis in adult teleosts is merely the continuation of an embryonic phase or a distinct process involving adult specific mechanisms for stemness maintenance.