Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:B0FTZ7 (catenin)
 18,795 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Loss of histotypic organization of epithelial cells is a common feature in normal development as well as in the invasion of carcinomas. Here we show that the v-src oncogene is a potent effector of epithelial differentiation and invasiveness. MDCK epithelial cells transformed with a temperature-sensitive mutant of v-src exhibit a strictly epithelial phenotype at the nonpermissive temperature for pp60v-src activity (40.5 degrees C) but rapidly loose cell-to-cell contacts and acquire a fibroblast-like morphology after culture at the permissive temperature (35 degrees C). Furthermore, the invasiveness of the cells into collagen gels or into chick heart fragments was increased at the permissive temperature. The profound effects of v-src on intercellular adhesion were not linked to changes in the levels of expression of the epithelial cell adhesion molecule E-cadherin. Rather, we observed an increase in tyrosine phosphorylation of E-cadherin and, in particular, of the associated protein beta-catenin. These results suggest a mechanism by which v-src counteracts junctional assembly and thereby promotes invasiveness and dedifferentiation of epithelial cells through phosphorylation of the E-cadherin/catenin complex.
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PMID:Loss of epithelial differentiation and gain of invasiveness correlates with tyrosine phosphorylation of the E-cadherin/beta-catenin complex in cells transformed with a temperature-sensitive v-SRC gene. 842

Various types of tumors show aberrant expression and overexpression of epidermal growth factor (EGF) receptor and the degree of receptor expression correlates with a malignant phenotype in many epithelial tumors. However, in vitro evidence supporting the advantageous role of receptor overexpression is deficient. In this study, we compared the effects of exogenous EGF on the cell colony morphology in monolayer and collagen gel culture between HSC-1 squamous carcinoma cells overexpressing EGF receptor and their revertant subline cells. These cells formed coherent cell colonies under routine culture conditions, but addition of EGF induced dissociation of cell colonies within 24 h in the parent HSC-1 cells, though not in the subline cells. Since the colony dissociation apparently involved loss of cell-cell adhesion, we also studied the effects of EGF on E-cadherin expression and its function. Cell aggregation assays showed that EGF reduced E-cadherin function dose-dependently in the parent cells, but not in the subline cells. However, immunoblotting analysis and ELISA showed the absence of downregulation or degradation of E-cadherin. Instead, EGF tyrosine phosphorylated cadherin/catenin complex components including beta-catenin and increased the detergent solubility of E-cadherin in the parent cells. These results suggest that EGF modified the functional association between E-cadherin and actin filament through tyrosine phosphorylation of the cadherin/catenin complex and thereby made the adhesion molecule incompetent. Our results indicate that the ligand activation of overexpressed EGF receptor impairs E-cadherin-mediated cell-cell adhesion and causes dissociation of the squamous carcinoma cell colonies, which facilitates tumor cell invasion in vivo. This might be relevant to the advantageous role of EGF receptor overexpression in malignant phenotype of epithelial tumor cells.
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PMID:Ligand activation of overexpressed epidermal growth factor receptor results in colony dissociation and disturbed E-cadherin function in HSC-1 human cutaneous squamous carcinoma cells. 863 95

This paper is the first in a series aimed at understanding the role of beta-catenin in epithelial-mesenchymal transformation (EMT) and acquisition of mesenchymal invasive motility. Here, we compare the expression of this and related molecules in the two major tissue phenotypes, epithelial and mesenchymal, the latter including normal avian and mammalian fibroblasts and malignant human uveal melanoma cells. Previously, it was proposed that src initiates EMT by tyrosine phosphorylation of the cadherin/catenin complex resulting in a negative effect on epithelial gene expression. On the contrary, we found that although beta-catenin becomes diffuse in the cytoplasm during embryonic EMT, the cytoplasmic beta-catenin of the embryonic and adult mesenchymal cells we examined is not tyrosine phosphorylated. Pervanadate experiments indicate that cytoplasmic PTPases maintain this dephosphorylation. GSK-3beta is present, but little or no APC occurs in normal and neoplastic mesenchymal cells. The function of the nonphosphorylated cytoplasmic beta-catenin in mesenchyme may be related to invasive motility. Indeed, in order to invade extracellular matrix, transitional (Mel 252) melanoma cells transform from an epithelial to a mesenchymal phenotype with increased cytoplasmic beta-catenin. Moreover, antisense beta-catenin and plakoglobin ODNs inhibit Mel 252 and corneal fibroblast invasion of collagen. All fibroblastic, transitional, and spindle melanoma cells contain nuclear as well as cytoplasmic beta-catenin, but they are not significantly more invasive than normal fibroblasts that contain only cytoplasmic beta-catenin.
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PMID:Tissue-specific expression of beta-catenin in normal mesenchyme and uveal melanomas and its effect on invasiveness. 982 3

Catenins, a family of structurally related proteins, are involved in epidermal keratinocyte cell-cell adhesion by interacting through their central Armadillo repeats with the intracellular domains of cadherins, transmembrane components of the adhesion junctions. p120ctn is a catenin expressed in different isoforms due to alternative splicing and multiple translation start sites. BP180 is a collagenous transmembrane protein (type XVII collagen) localized to hemidesmosomal attachment complexes in basal keratinocytes. In this study, we have delineated the molecular interaction between these two proteins utilizing the yeast two-hybrid system, which was confirmed by an in vitro protein-protein interaction assay. Specifically, it was shown that an amino-terminal segment of BP180 (aa. 13-25) contains the information necessary for binding to p120ctn isoforms 1-3, but not to the isoform 4, suggesting that the interacting domain is located immediately upstream from the Armadillo repeats and is encoded by exons 5 and 6, which are subject to alternative splicing only in a minority of transcripts. In addition to epidermal keratinocytes, p120ctn was shown to be expressed in a variety of adult and fetal tissues as well as in a number of human tumors. The expression pattern of various p120ctn transcripts, reflecting alternative splicing of the 5' exons, was strikingly similar between the corresponding adult and fetal tissues, while the expression patterns were discordant between certain tumors and their normal parental tissues, suggesting a functional role for the tissue-specific expression of the p120ctn isoforms. Finally, the tissue-specific expression of BP180 was shown to partially overlap with that of p120ctn, suggesting that the interaction of these two proteins may contribute to the modulation of cell-cell/matrix interactions in such tissues.
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PMID:Human p120ctn catenin: tissue-specific expression of isoforms and molecular interactions with BP180/type XVII collagen. 1032 38

The cadherin-mediated cell-cell adhesion system plays a critical role in normal development and morphogenesis. Inactivation of this system is thought to be responsible for cancer invasion and metastasis. A human hepatocellular carcinoma (HCC) cell line, KYN-2, was observed to have great potential for intrahepatic metastasis when orthotopically implanted into the liver of SCID mice. In vitro cultures of KYN-2 cells showed that they formed trabecular structures in suspension but lost tight cell-cell adhesion and became scattered when attached to a substratum such as collagen or fibronectin. In response to adhesion to the substratum, subcellular colocalization of E-cadherin and actin filaments were shown to be reduced, and a significant amount of alpha-catenin was dissociated from the E-cadherin-catenin complex in KYN-2 cells. These changes of cell-cell adhesion were blocked by inhibitory monoclonal antibodies against beta1 and beta5 integrins. We found that c-Src was coimmunoprecipitated with E-cadherin-catenin complex and was tyrosine-dephosphorylated and activated in the adherent cells. The tyrosine dephosphorylation of c-Src was induced by cell adhesion to the substratum and inhibited by addition of inhibitory monoclonal antibodies against beta1 and beta5 integrins. These findings indicate that integrin-mediated cell-substratum adhesion inhibits cadherin-mediated cell-cell adhesion, possibly through c-Src activation, and suggest that this cross-talk mediates transient inactivation of the cadherin system and plays an important role in intrahepatic metastasis of human HCC. Modulation of this interaction might provide a new approach to prevent metastasis and recurrence of HCC.
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PMID:Loss of cell-cell contact is induced by integrin-mediated cell-substratum adhesion in highly-motile and highly-metastatic hepatocellular carcinoma cells. 1074 74

We have analysed the expression of cadherin/catenin complex molecules in PC C13 rat thyroid cells transformed in vitro with different oncogenes. No significant downregulation of either E-cadherin, alpha-, beta- and gamma-catenin was detected following the introduction of activated forms of myc, adenovirus E1A, ras, raf, myc + ras, E1A + raf. However, ras- and raf-transformed PC C13 cells showed altered adherens junctions. An altered distribution of cadherin/catenin complexes characterized by radially oriented membrane spikes perpendicular to cell edges was the most prominent feature evidenced by immunofluorescence. No beta1 integrin localization was observed in areas where this altered pattern of E-cadherin expression was detected. However, beta1 integrin subunit expression was detected at areas of cell-cell contact where E-cadherin showed a normal pattern of expression. Furthermore, ras- and raf-transformed PC C13 cells showed the ability to migrate in collagen gels, in contrast to their normal untransformed counterpart. Overexpression of beta1 integrin was found to restore normal E-cadherin localization at cell-cell contacts and to partially inhibit the ability to migrate in collagen gels. Finally, two cell lines obtained by ras transformation in vivo, and derived from a rat primary thyroid carcinoma (TK6) and its lung metastasis (MPTK6), were found to have lost gamma-catenin expression. TK6 lost also E-cadherin expression and membrane localization of alpha-catenin. These results suggest that: i) in vitro thyroid cell transformation is associated to a change in cadherin/catenin complexes distribution rather than to a decrease in expression; ii) in vivo transformation is associated to the loss of expression of some of these molecules likely due to tumor progression; iii) alterations in beta1 integrin subunit expression can result in changes in cadherin/catenin function thus implying that an integrin-cadherin synergy may exist in thyroid cells.
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PMID:Analysis of cadherin/catenin complexes in transformed thyroid epithelial cells: modulation by beta 1 integrin subunit. 1104 99

The extracellular matrix plays an important role in regulation of epithelial development and organization. To determine more precisely the function of extracellular matrix in this process, the initial steps in collagen-mediated formation of epithelial tubules were studied using a model cell culture system. Previous studies have demonstrated that incubation of Madin-Darby canine kidney (MDCK) epithelial cells with a collagen gel overlay induces (beta)1 integrin-regulated epithelial remodeling accompanied by extensive cell rearrangements and formation of epithelial tubules. During epithelial remodeling there was extensive disruption of the epithelial junctional complex. Progressive opening of tight junctions was observed over 8 hours using transepithelial resistance measurements and immunofluorescence microscopy demonstrated that tight and adherens junction proteins were dispersed throughout the apical and basolateral membranes. Junction complex disruption allowed the formation of apical cell extensions and subsequent migration of selected cell sheets from the epithelial monolayer. Confocal microscopy demonstrated the presence of adherens junction (E-cadherin, (alpha)-catenin, (beta)-catenin, plakoglobin) and desmosomal (desmoplakin-1/2, plakoglobin) proteins on, and within, cell extensions demonstrating that cell junctions had undergone considerable disassembly. However, groups of cell extensions appeared to be associated by E-cadherin/catenin-mediated interactions. Association of E-cadherin/catenin complexes with the epithelial cytoskeleton was analyzed by differential detergent extraction. SDS-PAGE and immunoblot analysis demonstrated that adherens junction proteins were primarily cytoskeleton-associated in control cells. During integrin-regulated remodeling, there was a progressive reduction in the interaction of adherens junction proteins with the cytoskeleton suggesting that they play an important role in the maintenance of epithelial integrity. Since loss of transepithelial electrical resistance and disruption of junctional complexes were inhibited by an antifunctional integrin antibody, we propose that activation of integrin signaling pathways regulate junctional complex stability, cell-cell interactions and cell migration. These observations provide evidence that integrin-regulated MDCK epithelial tubule formation can serve as a model system for studying rearrangements of epithelial sheets which occur during development.
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PMID:Integrin regulation of cell-cell adhesion during epithelial tubule formation. 1118 Nov 77

1-O-octadecyl-2-O-methyl-glycerophosphocholine (ET-18-OMe) is an analogue of the naturally occurring 2-lysophosphatidylcholine belonging to the class of antitumor lipids. Previously, we demonstrated that ET-18-OMe modulates cell-cell adhesion of human breast cancer MCF-7 cells. In the present study, we tested the effect of ET-18-OMe on adhesion, invasion and localisation of episialin and E-cadherin in MCF-7/AZ cells expressing a functional E-cadherin/catenin complex. The MCF-7/6 human breast cancer cells were used as negative control since their E-cadherin/catenin complex is functional in cells grown on solid substrate but not in suspension. The function of E-cadherin, a calcium-dependent transmembrane cell-cell adhesion and signal-transducing molecule, is disturbed in invasive cancers by mutation, loss of mRNA stability, proteolytic degradation, tyrosine phosphorylation of associated proteins and large cell-associated proteoglycans or mucin-like molecules such as episialin. Episialin, also called MUC1, is an anti-adhesion molecule that by its large number of glycosylated tandem repeats can sterically hinder the adhesive properties of other glycoproteins. ET-18-OMe inhibited the E-cadherin functions of MCF-7/AZ cells as measured by inhibition of fast and slow aggregation and by the induction of collagen invasion. These effects were enhanced by MB2, an antibody against E-cadherin and blocked by monoclonal antibodies (MAbs) 214D4 or M8 against episialin. ET-18-OMe had no influence on tyrosine phosphorylation of beta-catenin and the E-cadherin/catenin complex remained intact. Transcription, translation, protein turnover and cell surface localisation of episialin were not altered. ET-18-OMe induced finger-like extensions with clustering of episialin together with E-cadherin and carcinoembryonic antigen but not with occludin. In cells in suspension, ET-18-OMe caused a shift in the flow-cytometric profile of episialin toward a lower intensity for MCF-7/AZ cells. In contrast with MCF-7/AZ cells, the adhesion-deficient and noninvasive MCF-7/6 cells showed neither morphotypic changes nor induction of aggregation nor invasion in collagen I upon treatment with ET-18-OMe. Co-localisation of episialin with E-cadherin was rarely observed. We conclude that in the human breast cancer cells MCF-7/AZ, E-cadherin and episialin are key molecular players in the regulation of promotion and suppression of cell-cell adhesion and invasion.
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PMID:Alkyl-lysophospholipid 1-O-octadecyl-2-O-methyl- glycerophosphocholine induces invasion through episialin-mediated neutralization of E-cadherin in human mammary MCF-7 cells in vitro. 1130 87

E-cadherin-mediated cell-cell adhesion is reduced in epithelial tumors, which is thought to be a prerequisite to acquire invasive properties. We observed that several pancreatic carcinoma cell lines with high metastatic potential expressed normal levels of E-cadherin and possessed functional E-cadherin/catenin adhesion complexes. When the cell lines PANC-1, BxPC-3, and PaTu8988s were cultured either on type I or type III collagen, E-cadherin gene expression was repressed, and E-cadherin and catenin protein concentrations were reduced. In contrast, growth on fibronectin and collagen type IV had no influence. Collagen type I- or type III-dependent reduction of E-cadherin expression led to decreased cell-cell adhesion, increased proliferation, and migratory activity as well as morphological transformation. Overexpression of activated c-Src in PANC-1 cells mimicked collagen-induced E-cadherin down-regulation and changed the elevated cell proliferation and migration. Conversely, treatment of cells with the Src-inhibitors PP1 or herbimycin A resulted in complete suppression of collagen type I-induced E-cadherin decrease. Our data demonstrate that specific collagens are able to promote metastatic behavior by down-regulation of E-cadherin gene expression in a Src-kinase-dependent manner. This points toward a novel mechanism for substrate-dependent signaling and underlines the significance of extracellular matrix environment for tumor growth and invasiveness.
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PMID:Down-regulation of E-cadherin gene expression by collagen type I and type III in pancreatic cancer cell lines. 1130 15

Local inflammatory reactions affect the integrity of intestinal epithelial cells, such as E-cadherin-mediated cell-cell interactions. To elucidate this event, we investigated the effects of an inflammatory mediator, leukotriene D(4 )(LTD(4)), on the phosphorylation status and properties of vinculin, a multi-binding protein known to interact with both the E-cadherin-catenin complex and the cytoskeleton. Treatment of an intestinal epithelial cell line with LTD(4 )induced rapid tyrosine phosphorylation of vinculin, which was blocked by the Src family tyrosine kinase inhibitor PP1. Simultaneously, LTD(4) caused an increased association between vinculin and actin, and that association was decreased by PP1. LTD(4) also induced dissociation of vinculin from alpha-catenin without affecting the catenin complex itself. This dissociation was not blocked by PP1 but was mimicked by the protein kinase C (PKC) activator 12-O-tetradecanoylphorbol 13-acetate (TPA). Also, the PKC inhibitor GF109203X abolished both the LTD(4)- and the TPA-induced dissociation of vinculin from alpha-catenin. Furthermore, LTD(4) caused a colocalisation of vinculin with PKC-alpha in focal adhesions. This accumulation of vinculin was blocked by transfection with a dominant negative inhibitor of PKC (PKC regulatory domain) and also by preincubation with either GF109203X or PP1. Thus, various LTD(4)-induced phosphorylations of vinculin affect the release of this protein from catenin complexes and its association with actin, two events that are necessary for accumulation of vinculin in focal adhesions. Functionally this LTD(4)-induced redistribution of vinculin was accompanied by a PKC-dependent upregulation of active beta1 integrins on the cell surface and an enhanced beta1 integrin-dependent adhesion of the cells to collagen IV.
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PMID:Leukotriene D(4) affects localisation of vinculin in intestinal epithelial cells via distinct tyrosine kinase and protein kinase C controlled events. 1132 79


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