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Anomalous features of EMT during keratinocyte transformation.

Geiger T, Sabanay H, Kravchenko-Balasha N, Geiger B, Levitzki A - PLoS ONE (2008)

Bottom Line: Surprisingly, unlike "conventional EMT", these changes are associated with reduced Rac1-dependent cell migration.We monitored reduced Rac1-dependent migration also in the cervical cancer cell line SiHa.Therefore we can conclude that up to the stage of tumor formation migratory activity is eliminated.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Chemistry, Institute of Life Science, The Hebrew University, Jerusalem, Israel.

ABSTRACT
During the evolution of epithelial cancers, cells often lose their characteristic features and acquire a mesenchymal phenotype, in a process known as epithelial-mesenchymal transition (EMT). In the present study we followed early stages of keratinocyte transformation by HPV16, and observed diverse cellular changes, associated with EMT. We compared primary keratinocytes with early and late passages of HF1 cells, a cell line of HPV16-transformed keratinocytes. We have previously shown that during the progression from the normal cells to early HF1 cells, immortalization is acquired, while in the progression to late HF1, cells become anchorage independent. We show here that during the transition from the normal state to late HF1 cells, there is a progressive reduction in cytokeratin expression, desmosome formation, adherens junctions and focal adhesions, ultimately leading to poorly adhesive phenotype, which is associated with anchorage-independence. Surprisingly, unlike "conventional EMT", these changes are associated with reduced Rac1-dependent cell migration. We monitored reduced Rac1-dependent migration also in the cervical cancer cell line SiHa. Therefore we can conclude that up to the stage of tumor formation migratory activity is eliminated.

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Desmosomes and cytokeratin are gradually reduced in the course of transformation.A. Primary keratinocytes, early and late HF1 cells were examined by transmission electron microscopy (TEM). Arrows show representative desmosomes, and arrowheads point to areas of cytokeratin bundles. B. Representative immuno-fluorescence images of plakoglobin staining. Bar = 15 µm. C. Western blot analysis of plakoglobin expression in the primary keratinocytes, early and late HF1 cells. Graph shows quantification of three experiments.
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pone-0001574-g001: Desmosomes and cytokeratin are gradually reduced in the course of transformation.A. Primary keratinocytes, early and late HF1 cells were examined by transmission electron microscopy (TEM). Arrows show representative desmosomes, and arrowheads point to areas of cytokeratin bundles. B. Representative immuno-fluorescence images of plakoglobin staining. Bar = 15 µm. C. Western blot analysis of plakoglobin expression in the primary keratinocytes, early and late HF1 cells. Graph shows quantification of three experiments.

Mentions: The pattern of cytokeratin expression is a marker for the degree of cell differentiation and transformation [6]. It was shown that during EMT, cytokeratin levels are reduced, while vimentin, the mesenchymal intermediate filament species is elevated [2], [6], [7], [17], [18]. We monitored decreased abundance of intermediate filaments at early stages of transformation by transmission electron microscopy (TEM). In the primary keratinocytes we observed massive distribution of cytokeratin bundles throughout the cell, while early HF1 cells had a delicate network of intermediate filaments, which was further reduced upon progression to late HF1 cells (Figure 1A).


Anomalous features of EMT during keratinocyte transformation.

Geiger T, Sabanay H, Kravchenko-Balasha N, Geiger B, Levitzki A - PLoS ONE (2008)

Desmosomes and cytokeratin are gradually reduced in the course of transformation.A. Primary keratinocytes, early and late HF1 cells were examined by transmission electron microscopy (TEM). Arrows show representative desmosomes, and arrowheads point to areas of cytokeratin bundles. B. Representative immuno-fluorescence images of plakoglobin staining. Bar = 15 µm. C. Western blot analysis of plakoglobin expression in the primary keratinocytes, early and late HF1 cells. Graph shows quantification of three experiments.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2215777&req=5

pone-0001574-g001: Desmosomes and cytokeratin are gradually reduced in the course of transformation.A. Primary keratinocytes, early and late HF1 cells were examined by transmission electron microscopy (TEM). Arrows show representative desmosomes, and arrowheads point to areas of cytokeratin bundles. B. Representative immuno-fluorescence images of plakoglobin staining. Bar = 15 µm. C. Western blot analysis of plakoglobin expression in the primary keratinocytes, early and late HF1 cells. Graph shows quantification of three experiments.
Mentions: The pattern of cytokeratin expression is a marker for the degree of cell differentiation and transformation [6]. It was shown that during EMT, cytokeratin levels are reduced, while vimentin, the mesenchymal intermediate filament species is elevated [2], [6], [7], [17], [18]. We monitored decreased abundance of intermediate filaments at early stages of transformation by transmission electron microscopy (TEM). In the primary keratinocytes we observed massive distribution of cytokeratin bundles throughout the cell, while early HF1 cells had a delicate network of intermediate filaments, which was further reduced upon progression to late HF1 cells (Figure 1A).

Bottom Line: Surprisingly, unlike "conventional EMT", these changes are associated with reduced Rac1-dependent cell migration.We monitored reduced Rac1-dependent migration also in the cervical cancer cell line SiHa.Therefore we can conclude that up to the stage of tumor formation migratory activity is eliminated.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Chemistry, Institute of Life Science, The Hebrew University, Jerusalem, Israel.

ABSTRACT
During the evolution of epithelial cancers, cells often lose their characteristic features and acquire a mesenchymal phenotype, in a process known as epithelial-mesenchymal transition (EMT). In the present study we followed early stages of keratinocyte transformation by HPV16, and observed diverse cellular changes, associated with EMT. We compared primary keratinocytes with early and late passages of HF1 cells, a cell line of HPV16-transformed keratinocytes. We have previously shown that during the progression from the normal cells to early HF1 cells, immortalization is acquired, while in the progression to late HF1, cells become anchorage independent. We show here that during the transition from the normal state to late HF1 cells, there is a progressive reduction in cytokeratin expression, desmosome formation, adherens junctions and focal adhesions, ultimately leading to poorly adhesive phenotype, which is associated with anchorage-independence. Surprisingly, unlike "conventional EMT", these changes are associated with reduced Rac1-dependent cell migration. We monitored reduced Rac1-dependent migration also in the cervical cancer cell line SiHa. Therefore we can conclude that up to the stage of tumor formation migratory activity is eliminated.

Show MeSH
Related in: MedlinePlus