The heparan sulfate proteoglycan syndecan-1 regulates colon cancer stem cell function via a focal adhesion kinase—Wnt signaling axis

In colon cancer, downregulation of the transmembrane heparan sulfate proteoglycan syndecan‐1 (Sdc‐1) is associated with increased invasiveness, metastasis, and dedifferentiation. As Sdc‐1 modulates signaling pathways relevant to stem cell function, we tested the hypothesis that it may regulate a tumor‐initiating cell phenotype. Sdc‐1 small‐interfering RNA knockdown in the human colon cancer cell lines Caco2 and HT‐29 resulted in an increased side population (SP), enhanced aldehyde dehydrogenase 1 activity, and higher expression of CD133, LGR5, EPCAM, NANOG, SRY (sex‐determining region Y)‐box 2, KLF2, and TCF4/TCF7L2. Sdc‐1 knockdown enhanced sphere formation, cell viability, Matrigel invasiveness, and epithelial‐to‐mesenchymal transition‐related gene expression. Sdc‐1‐depleted HT‐29 xenograft growth was increased compared to controls. Decreased Sdc‐1 expression was associated with an increased activation of β1‐integrins, focal adhesion kinase (FAK), and wingless‐type (Wnt) signaling. Pharmacological FAK and Wnt inhibition blocked the enhanced stem cell phenotype and invasive growth. Sequential flow cytometric SP enrichment substantially enhanced the stem cell phenotype of Sdc‐1‐depleted cells, which showed increased resistance to doxorubicin chemotherapy and irradiation. In conclusion, Sdc‐1 depletion cooperatively enhances activation of integrins and FAK, which then generates signals for increased invasiveness and cancer stem cell properties. Our findings may provide a novel concept to target a stemness‐associated signaling axis as a therapeutic strategy to reduce metastatic spread and cancer recurrence.DatabasesThe GEO accession number of the Affymetrix transcriptomic screening is GSE58751

Transmembrane protein TMEM230, regulator of metalloproteins and motor proteins in gliomas and gliosis

Glial cells provide physical and chemical support and protection for neurons and for the extracellular compartments of neural tissue through secretion of soluble factors, insoluble scaffolds, and vesicles. Additionally, glial cells have regenerative capacity by remodeling their physical microenvironment and changing physiological properties of diverse cell types in their proximity. Various types of aberrant glial and macrophage cells are associated with human diseases, disorders, and malignancy. We previously demonstrated that transmembrane protein, TMEM230 has tissue revascularization and regenerating capacity by its ability to secrete pro-angiogenic factors and metalloproteinases, inducing endothelial cell sprouting and channel formation. In healthy normal neural tissue, TMEM230 is predominantly expressed in glial and marcophate cells, suggesting a prominent role in neural tissue homeostasis. TMEM230 regulation of the endomembrane system was supported by co-expression with RNASET2 (lysosome, mitochondria, and vesicles) and STEAP family members (Golgi complex). Intracellular trafficking and extracellular secretion of glial cellular components are associated with endocytosis, exocytosis and phagocytosis mediated by motor proteins. Trafficked components include metalloproteins, metalloproteinases, glycans, and glycoconjugate processing and digesting enzymes that function in phagosomes and vesicles to regulate normal neural tissue microenvironment, homeostasis, stress response, and repair following neural tissue injury or degeneration. Aberrantly high sustained levels TMEM230 promotes metalloprotein expression, trafficking and secretion which contribute to tumor associated infiltration and hypervascularization of high tumor grade gliomas. Following injury of the central nervous or peripheral systems, transcient regulated upregulation of TMEM230 promotes tissue wound healing, remodeling and revascularization by activating glial and macrophage generated microchannels/microtubules (referred to as vascular mimicry) and blood vessel sprouting and branching. Our results support that TMEM230 may act as a master regulator of motor protein mediated trafficking and compartmentalization of a large class of metalloproteins in gliomas and gliosis

Wear Improvements Induced by Thermally Grown Oxide Layers and by Nitrogen Ion Implantation

Mild steels which have been either thermally oxidized near 300°C or implanted with nitrogen ions have been wear tested using a modified Falex Lubricant Testing machine. Both these treatments cause similar, much reduced wear rates which are about an order of magnitude better than in untreated samples. Specimens worn after treatments by both methods have been examined in detail using scanning electron microscopy and Auger spectroscopy. It is concluded that the wear induced by oxidation is the same as the wear induced by nitrogen ion implantation. Both of these treatments acted to initiate favorable sustained oxide wear and confirm the Initiator/Sustainer model. Additional studies have been done on oxidized samples using a variety of sample processing techniques and sequences including oxide layer stripping, wear recycling, and annealing. These studies clearly show that favorable wear results were caused by the grown oxide layer and not by the heat treatment. Also, it has been found that the favorable oxide wear can be stopped and started numerous times since it is able to reinitiate and sustain itself. However, if a worn oxide layer is stripped from a sample just prior to the wear run, favorable wear does not occur unless the sample was oxidized or favorably worn in the last few weeks. This occurs because wear favorable chemistry at the oxide/metal interface anneals at room temperature. Other discussions of the wear initiating and sustaining processes are presented

Nitrogen Implantation of Steels: A Treatment Which Can Initiate Sustained Oxidative Wear

Falex wear tests on mild (SAE 3135) steel samples treated by either nitrogen implantation (2.5 × 1017 N2+ cm-2 at 180 ke V) or low temperature (about 315 °C) oxidation are reported. The results show that both treatments lead to about an order-of-magnitude reduction in the long-term wear rate of the steel. In addition to the wear rate measurements, the wear member asymmetry behavior, scanning electron microscopy studies, Auger spectra and sputter profiles all indicate that the wear modes induced by both treatments are the same and are oxidative wear. These results confirm the previously proposed initiator-sustainer wear model in which implanted nitrogen simply acts as an initiator of favorable oxidative wear but is not directly involved in maintaining the sustained wear resistance. Possible mechanisms for both the initiation process and the sustained wear process are reviewed and discussed. © 1987

Ion Implantation and Thermal Oxidation as Treatments to Initiate Sustained Oxide Wear in Steels

Both nitrogen implantation (2.5×1017 N +2 /cm2 at 180 keV) and low-temperature (≊315°C) oxidation are shown to produce an order of magnitude reduction in the wear rate of an SAE 3135 steel. Measurements of the wear rates, wear member asymmetry behavior, and both scanning electron microscopy and Auger studies indicate that the same mechanism leads to the much improved wear rates. Both treatments substantiate the initiator/sustainer wear model, in which the initiation treatment reduces the wear to a low value that is sustained throughout the wear test. The sustained stage is a form of mild wear, which involves oxygen and appears to be oxidative wear

Geometric and Computational Models of Chromatin Fibre Folding for Human Embryonic Stem Cells

AbstractIn this study we analyze the chromatin state of human pluripotent stem cells by geometric and computational modelling of fibre conformation. The model takes into account local structure of chromatin organized into euchromatin, permissive for gene activation, and heterochromatin, transcriptionally silenced. Euchromatin was modelled using linear DNA while heterochromatin by means of a solenoid structure in which DNA winds onto six nucleosome spools per turn. Two geometric models are presented and are compared in terms of geometric quantities. The models are tested using in vivo data generated from chromatin human immunoprecipitation from embryonic stem cells. This study provides insight for identifying the relationships between chromosome geometry and epigenomic processes associated with chromatin remodeling, cellular reprograming and maintenance of cellular pluripotency

Identification of functionally related genes using data mining and data integration: a breast cancer case study

Abstract Background The identification of the organisation and dynamics of molecular pathways is crucial for the understanding of cell function. In order to reconstruct the molecular pathways in which a gene of interest is involved in regulating a cell, it is important to identify the set of genes to which it interacts with to determine cell function. In this context, the mining and the integration of a large amount of publicly available data, regarding the transcriptome and the proteome states of a cell, are a useful resource to complement biological research. Results We describe an approach for the identification of genes that interact with each other to regulate cell function. The strategy relies on the analysis of gene expression profile similarity, considering large datasets of expression data. During the similarity evaluation, the methodology determines the most significant subset of samples in which the evaluated genes are highly correlated. Hence, the strategy enables the exclusion of samples that are not relevant for each gene pair analysed. This feature is important when considering a large set of samples characterised by heterogeneous experimental conditions where different pools of biological processes can be active across the samples. The putative partners of the studied gene are then further characterised, analysing the distribution of the Gene Ontology terms and integrating the protein-protein interaction (PPI) data. The strategy was applied for the analysis of the functional relationships of a gene of known function, Pyruvate Kinase, and for the prediction of functional partners of the human transcription factor TBX3. In both cases the analysis was done on a dataset composed by breast primary tumour expression data derived from the literature. Integration and analysis of PPI data confirmed the prediction of the methodology, since the genes identified to be functionally related were associated to proteins close in the PPI network. Two genes among the predicted putative partners of TBX3 (GLI3 and GATA3) were confirmed by in vivo binding assays (crosslinking immunoprecipitation, X-ChIP) in which the putative DNA enhancer sequence sites of GATA3 and GLI3 were found to be bound by the Tbx3 protein. Conclusion The presented strategy is demonstrated to be an effective approach to identify genes that establish functional relationships. The methodology identifies and characterises genes with a similar expression profile, through data mining and integrating data from publicly available resources, to contribute to a better understanding of gene regulation and cell function. The prediction of the TBX3 target genes GLI3 and GATA3 was experimentally confirmed.</p