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Query: KEGG:D02003 (NBT)
 1,323 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mesenchymal cell lines derived from fetal rat urogenital sinus organ cultures have been characterized to establish an in vitro system for addressing growth and differentiation regulatory factors involved in mesenchymal-epithelial interactions during prostate morphogenesis. A continuous cell line was developed and designated U4F. Immunocytochemical analysis showed vimentin intermediate filament content confirming a mesenchymal origin. Previous studies with urogenital sinus organ cultures have reported the expression of a negative growth activity, which is stimulatory to protein synthesis and secretion and alters phenotypic morphology of NBT-II bladder epithelial cells. Subconfluent and confluent U4F monolayers did not produce this growth inhibitory activity. Foci of stacked cells were observed 3 wk postconfluency, which evolved into multicellular spheroids. The negative growth activity was expressed in the conditioned medium coordinate with spheroid formation. Transplanted spheroids continued to express the growth inhibitory activity. Morphologic analysis of spheroids showed a cellular capsule and a core of extracellular matrix. A continuous cell strain (U4F1) with altered phenotypic properties, arose spontaneously from long-term U4F cultures. The U4F1 cell strain did not form spheroids, yet expressed the negative growth activity constitutively in monolayer culture. Analyses of physicochemical, immunological, and biological properties showed the activity is identical in conditioned media from urogenital sinus organ cultures, U4F spheroids, and U4F1 monolayers. Based on the combined properties, this activity cannot be ascribed to previously characterized negative growth factors. The establishment of this mesenchymal cell culture system will aid in the further identification of paracrine-acting growth and differentiation regulatory factors secreted by fetal mesenchyme.
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PMID:Characterization of a fetal urogenital sinus mesenchymal cell line U4F: secretion of a negative growth regulatory activity. 173 May 68

Two distinct mechanisms by which bladder carcinoma cells of the NBT-II cell line dissociate and migrate away from an in vitro reconstituted epithelial sheet were examined as regards intercellular adhesion and cell locomotion. Scattering of NBT-II bladder carcinoma cell line was promoted by 2 distinct culture protocols: (i) deposition of some components of the extracellular matrix onto the culture substratum (glass or plastic) induced cell dispersion of the epithelial sheet of carcinoma cells, and (ii) addition of Ultroser G, a serum substitute, to the culture medium induced scattering and acquisition of motility of NBT-II cells. Under both culture conditions, NBT-II cells dissociated, lost their epithelial morphology, acquired fibroblastic shape and migrated actively. We show that, among different extracellular matrix proteins, only collagens were able to promote the transition towards fibroblastic phenotype (referred as epithelium-to-mesenchyme transition or EMT). Furthermore, the native 3-dimensional helical structure of collagens was required for their function. During induction of EMT of NBT-II cells with Ultroser G, the junctions between epithelial cells were split, polarized epithelial cell organization was lost, and the resulting individual cells became motile and assumed a spindle-like fibroblastoid appearance. Using immunofluorescence microscopy techniques, we demonstrate that this change is accompanied by redistribution of desmosomal plaque proteins (desmoplakins, desmoglein, plakoglobin) and by reorganization of the cytokeratin and the actin-fodrin filament systems. Intermediate-sized filaments of the vimentin type were formed de novo in the fibroblastoid cell form. The observed transition towards fibroblastic phenotype (epithelium-to-mesenchyme transition or EMT) was fully reversed by removing the inducing factors from the culture medium, as shown by the disappearance of vimentin filaments and the reappearance of desmosomes in the newly formed epithelial cells.
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PMID:Reversible transition towards a fibroblastic phenotype in a rat carcinoma cell line. 250 87

Changes of cell morphology and the state of differentiation are known to play important roles in embryogenesis as well as in carcinogenesis. Examples of particularly profound changes are the conversions of epithelial to mesenchymal cells; i.e., the dissociation of some or all polygonal, polar epithelial cells and their transformation into elongate, fibroblastoid cells of high motility. As an in vitro model system for such changes in cell morphology, we have used cell cultures of the rat bladder carcinoma-derived cell line NBT-II which, on exposure to inducing medium containing a commercial serum substitute (Ultroser G), show an extensive change in their organization (epithelial-mesenchymal transition): the junctions between the epithelial cells are split, the epithelial cell organization is lost, and the resulting individual cells become motile and assume a spindle-like fibroblastoid appearance. Using immunofluorescence microscopy and biochemical protein characterization techniques, we show that this change is accompanied by a redistribution of desmosomal plaque proteins (desmoplakins, desmoglein, plakoglobin) and by a reorganization of the cytokeratin and the actin-fodrin filament systems. Moreover, intermediate-sized filaments of the vimentin type are formed in the fibroblastoid cells. We demonstrate that the modulation of desmosomal proteins, specifically an increase in soluble desmoplakins, is a relatively early event in cell dissociation and in epithelial-mesenchymal transition. In this process, a latent period of 5 h upon addition of inducing medium precedes the removal of these desmosomal components from the plasma membrane. The transition, which is reversible, is dependent on continued protein synthesis and phosphorylation but not on the presence of the inducing medium beyond the initial 2-h period. We discuss the value of this experimental system as a physiologically relevant approach for studying the regulation of the assembly and disassembly of desmosomes and other intercellular adhesion structures, and as a model of the conversion of cells from one state of differentiation into another.
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PMID:Rearrangements of desmosomal and cytoskeletal proteins during the transition from epithelial to fibroblastoid organization in cultured rat bladder carcinoma cells. 267 20

The involvement of Src kinase during carcinoma metastasis has been explored by using the NBT-II rat carcinoma cell line, which can be induced to scatter in vitro through Src activity. Here we show that Src activity was not required for growth of tumors derived from NBT-II cells injected into nude mice. In contrast, the presence of micrometastases was strictly dependent on Src, since the percentage of mice bearing metastases was dramatically reduced by the expression of a dominant-negative mutant of Src (SrcK-) or of Csk, the natural inhibitor of Src. Furthermore, metastatic cells originating from NBT-II cells displayed a Src activity higher than the parental cells, confirming that Src gives a selective advantage during the metastatic process. Finally, anatomopathological analysis of the primary tumors arising from NBT-II cells expressing Csk or SrcK- constructs revealed a highly differentiated epithelial phenotype contrasting with the poor differentiation of tumors derived from parental cells. The differentiated phenotype correlated with the presence of desmosomes at the cell periphery and the absence of vimentin intermediate filaments. Altogether, these data demonstrate that Src activity correlates with the loss of epithelial differentiation concomitantly with the increase of the metastatic potential of carcinoma cells.
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PMID:Src kinase contributes to the metastatic spread of carcinoma cells. 1194 18