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Proteomic profiling reveals that DPP4 overexpression increases cell adhesion, inhibits cell migration, and restores androgen sensitivity in prostate cancer.

Dipeptidyl peptidase-4 (DPP4), a serine protease with both enzymatic and non-enzymatic roles, has emerged as a context-dependent modulator of tumor progression. In the present study, we investigated the expression and function of DPP4 in androgen-sensitive and castration-resistant prostate cancer (CRPC) models. Proteomic analysis of androgen-resistant prostate cells overexpressing DPP4 identified the involvement of the cellular adhesion molecules pathway. In prostate cells, lentiviral-mediated DPP4 overexpression restored androgen receptor signaling, inhibited epithelial-to-mesenchymal transition, and reduced cell migration, whereas DPP4 silencing produced the opposite effects. We demonstrate that DPP4 expression is down-regulated in CRPC cells and that treatment with capsaicin (CAP), a bioactive compound derived from red peppers, restores DPP4 expression. Moreover, DPP4 restoration by CAP suppresses prostate tumorigenesis in the TRAMP mice in vivo model of prostate cancer. Our results suggest that DPP4 could be a new target for CRPC.

Male

Ganglioside inhibition of fibronectin-mediated cell adhesion to collagen.

Fibronectin mediates the adhesion of cells to collagen by first binding to the collagen substrate, followed by attachment of the cells to the fibronectin-collagen complex. Bovine brain gangliosides were found to block fibronectin-mediated cell adhesion to collagen in a concentration-dependent manner. The gangliosides did not block the binding of fibronectin to collagen but did prevent the attachment of the cells to the fibronectin-collagen complex. Of the individual gangliosides tested, GT1 and GD1a were the most effective inhibitors followed by GD1b greater than GM1 greater than GM2; GM3 was not an inhibitor. The inhibition of cell adhesion also was observed with the oligosaccharide portion of the gangliosides, but not with ceramides or with a variety of free sugars or glycosaminoglycans. Mild periodate oxidation of mixed gangliosides or of GD1a modified their sialic acid residues and the oxidized gangliosides were no longer inhibitory; subsequent reduction with NaBH4 did not restore the inhibitory activity of the modified gangliosides. These results suggest that specific gangliosides or related sialic acid-containing glycoconjugates on the cell surface may act as the receptors for fibronectin.

Animals

Cell adhesion.

Before cells can adhere to a surface, the atoms forming the adhesive bonds must come to within 0.5 nanometers of each other. Distances of this order may not correspond to the averaged electron micrographic data. The events leading to close approach of parts of cells are discussed in terms of electrical parameters, with an emphasis on the surface heterogeneities of cellular adherends. The distinct phenomenon of cell detachment is not simply the reverse of cell adhesion, and must be measured by different techniques. The effects of various pathophysiologic factors on cell attachment and detachment is discussed, with illustrative examples of direct and indirect factors. These include regeneration, degeneration, metabolic inhibitors, endotoxin and antisera. It is concluded the stability of the union between cells and teeth represents a delicate balance between factors promoting contact and initial adhesions, factors strengthening the adhesive interphase and factors promoting separation.

Antimetabolites

Functional correlation between cell adhesive properties and some cell surface proteins.

The adhesive properties of Chinese hamster V79 cells were analyzed and characterized by various cell dissociation treatments. The comparisons of aggregability among cells dissociated with EDTA, trypsin + Ca2+, and trypsin + EDTA, revealed that these cells have two adhesion mechanisms, a Ca2+-independent and a Ca2+-dependent one. The former did not depend on temperature, whereas the latter occurred only at physiological temperatures. Both mechanisms were trypsin sensitive, but the Ca2+-dependent one was protected by Ca2+ against trypsinization. In morphological studies, the Ca2+-independent adhesion appeared to be a simple agglutination or flocculation of cells, whereas the Ca2+-dependent adhesion seemed to be more physiological, being accompanied by cell deformation resulting in the increase of contact area between adjacent cells. Lactoperoxidase-catalyzed iodination of cell surface proteins revealed that several proteins are more intensely labeled in cells with Ca2+-independent adhesiveness than in cells without that property. It was also found that a cell surface protein with a molecular weight of approximately 150,000 is present only in cells with Ca2+-dependent adhesiveness. The iodination and trypsinization of this protein were protected by Ca2+, suggesting its reactivity to Ca2+. Possible mechanisms for each adhesion property are discussed, taking into account the correlation of these proteins with cell adhesiveness.

Animals

Human lymphoblastoid cell variants defective in cell-cell adhesion.

Adhesion mutants were selected from a human lymphoblastoid cell line. Initially, cells were selected on the basis of survival in serum-free medium. Subclones that grow as single cells rather than macroscopic aggregates were selected from the serum-independent variant. The defect in cell-cell adhesion is stable over many generations and is not corrected by growth in serum or the presence of serum in the culture medium. Analysis of mixed cultures composed of adhesive cells and nonadhesive cells indicates that the two cell types do not interact to form mixed aggregations. Furthermore, those results suggest that the adhesion-deficient phenotype does not result from the production of a transferable inhibitor. In a previous study [Whipple, A.P., Dalvin, M. & Millis, A.J.T. (1978) Exp. Cell Res. 116, 457-461], we found that the growth rate in serum-containing medium is identical for the two classes of cells. This suggests that cell-cell adhesion is not a critical factor in the growth of these cells.

Cell Adhesion

The relation of temperature and lipid composition to cell adhesion.

We have examined as a function of temperature the effect of changes in the composition of the fatty acid chains of membrane phospholipids on the rate of cell to cell adhesion in the neuronal cell line B103. The rate of cell to cell adhesion in this cell line is highly temperature dependent but is not influenced by changes in the fatty acid composition of the plasma membrane generated by growing the cells either in the presence of oleic acid or elaidic acid. In contrast the temperature dependence of the rate of cell to cell adhesion, measured in a monolayer adhesion assay, is highly dependent on the shear force used during the assay. A two-step model of cell to cell adhesion involving multiple adhesion ligands is presented which can be used to explain these observations.

Cell Adhesion

Characteristics and functions of a cell adhesion molecule PvCadN in Penaeus vannamei during WSSV infection.

Cell adhesion not only maintains the integrity of the organism, but also plays an important role in the immune system, which is involved in modulation in the interaction between host and virus. In this study, a novel cell adhesion molecule from Penaeus vannamei, designated as PvCadN, was investigated. It had the typical molecular characteristics of cadherin family, with multiple extracellular cadherin repeat domains, a transmembrane region, and a conserved β-catenin-binding motif. Pvcadn is expressed ubiquitously across all detected tissues, with the highest transcriptional level in gills. RNA interference-mediated silencing of pvcadn significantly impaired the adhesion ability of shrimp hemocytes. Upon WSSV infection, pvcadn showed a tissue-specific expression pattern, with upregulation in gills and downregulation in hemocytes. Knockdown of pvcadn markedly suppressed the transcription of WSSV immediate-early gene ie1 and replication of the viral genome in vivo, suggesting that PvCadN acted as a potential virus-associated molecule. Furthermore, it was found that PvCadN was regulated by Lvβ-catenin, a core molecule in the Wnt signaling pathway that functions in innate immunity, at the transcriptional and protein levels. Silencing of lvβ-catenin significantly downregulated pvcadn transcription, and Lvβ-catenin bound directly to the Cadherin C domain of PvCadN. In summary, the study revealed that PvCadN was a key cell adhesion molecule involved in WSSV infection, which was regulated by Lvβ-catenin. Our findings will provide fundamental data for further investigation into cadherin-mediated immune regulation in shrimp, and offer new insights for the prevention and control of WSSV.

Animals

An electron microscopic study of tumour cell adhesiveness induced by aggregation promoting factor from rat ascites hepatoma cells.

A substance capable of inducing tumour cell aggregation, which is supposed to be a glycoprotein showing noncytotoxicity, was separated from rat ascites hepatoma cells and partially purified by chromatography. Adhesiveness of rat ascites hepatoma cells induced by this substance was characterized by gradual development of known binding structures during a period of 24 h after contact with the substance; simple apposition and intermediate junctions developed in the early stage, and desmosomes and focal tight junctions in the later stage. It was assumed that the substance might be involved in the development of such binding structures as a triggering mechanism of tumour cell adhesiveness.

Animals

Knockdown Proteomics Reveals USP7 as a Regulator of Cell-Cell Adhesion in Colorectal Cancer via AJUBA.

Ubiquitin-specific protease 7 (USP7) is implicated in many cancers including colorectal cancer in which it regulates cellular pathways such as Wnt signaling and the P53-MDM2 pathway. With the discovery of small-molecule inhibitors, USP7 has also become a promising target for cancer therapy and therefore systematically identifying USP7 deubiquitinase interaction partners and substrates has become an important goal. In this study, we selected a colorectal cancer cell model that is highly dependent on USP7 and in which USP7 knockdown significantly inhibited colorectal cancer cell viability, colony formation, and cell-cell adhesion. We then used inducible knockdown of USP7 followed by LC-MS/MS to quantify USP7-dependent proteins. We identified the Ajuba LIM domain protein as an interacting partner of USP7 through co-IP, its substantially reduced protein levels in response to USP7 knockdown, and its sensitivity to the specific USP7 inhibitor FT671. The Ajuba protein has been shown to have oncogenic functions in colorectal and other tumors, including regulation of cell-cell adhesion. We show that both knockdown of USP7 or Ajuba results in a substantial reduction of cell-cell adhesion, with concomitant effects on other proteins associated with adherens junctions. Our findings underlie the role of USP7 in colorectal cancer through its protein interaction networks and show that the Ajuba protein is a component of USP7 protein networks present in colorectal cancer.

Ubiquitin-Specific Peptidase 7

Concanavalin A surface receptors and cytoplasmic actin in cell adhesion.

A double immunofluorescence staining technique to locate concanavalin A (Con A) surface receptors and cytoplasmic actin in the same cell was applied to monolayer cultures of rat foetal fibroblasts during cell detachment induced by trypsin and during cell attachment to glass substratum. Con A receptors were demonstrated by fluorescein-isothiocyanate-labelled Con A (FITC-Con A) and actin by specific anti-actin antibody (AAA) traced with rhodamine-labelled goat anti-human globulin (R-AHG). Untreated, control cells had an elongated shape, Con A receptors restricted to cell margins and prominent actin filaments. After 2 min treatment with 0.001% trypsin the cells became angular with Con A receptors in clusters and actin in a diffuse or aggreagate staining pattern. Progressive cell rounding followed and this was accompanied by the development of long, thin, arborized cell processes, studded with Con A receptors and containing fine actin filaments. Complete cell rounding preceded cell detachment. The sites of detached cells were marked by fine aggregates containing Con A receptors and actin. In cells attaching to a glass substratum, actin was present in a diffusely stained or aggregate pattern in round cells, in filaments restricted to cell margins in partially spread cells and in numerous filaments in fully spread cells. Con A receptors were present in clusters in round cells, in clusters or caps in partially spread cells and in cell margins in fully spread cells. Binding of FITC-Con A to partially spread cells resulted in dissolution of the few, newly formed, actin filaments. We believe our observations are consistent with the idea that actin filaments, formed during cell attachment, contribute towards the maintenance of cell adhesion by helping in the preservation of cell shape and by anchorage of Con A receptors at points of cell attachment to the substratum.

Actins

Cell adhesion to substrates containing adsorbed or attached IgG.

When most mammalian cells are propagated in tissue culture, they are attached to a solid surface. This surface is commonly covered with a layer of serum protein. In this study we looked at the effect of the protein layer on the interaction between the cells and the surface by precoating the surface with various pure protein molecules. We found no differences between surfaces covered with pure protein layers and those covered with serum proteins except when antibody molecules were used. In all cases the cell types used avoided surfaces covered with antibody molecules. Previously, other investigators have established that some cells belonging to the immunology system are attracted to such surfaces.

Antigen-Antibody Complex

Altered ECM deposition and cell adhesion signaling in a human cortical organoid model of fragile X syndrome.

Fragile X Syndrome (FXS) is the most common inherited intellectual disability, and the most common monogenic cause of autism spectrum disorder (ASD). It is caused by epigenetic silencing of the FMR1 gene leading to the loss of FMRP, an RNA-binding protein that regulates local mRNA translation in neuronal dendrites, crucial for synapse development. Three-dimensional (3D) brain organoid models derived through in vitro differentiation of pluripotent stem cells offer a powerful tool to dissect the underlying mechanisms of neurodevelopmental disorders. Here, we generated human FXS and control organoids using isogenic human embryonic stem cell clones with and without the FXS mutation. Our results show that mature FXS cortical brain organoids can be derived by inhibiting the TGFβ and Wnt pathways. Moreover, expression analyses including immunofluorescence, qRT-PCR, proteomics and western blotting reveal altered levels of neuronal markers and ECM deposition along with modulated downstream signaling molecules. Interestingly, in silico analysis of proteomics revealed several altered pathways, such as cell adhesion, regulation of neurogenesis and cell cycle that are implicated in FXS. Collectively, our unique FXS-organoids derived from isogenic hESC lines may serve as a model for studying the pathology of FXS disorder and for developing therapeutical intervention.

Humans