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The lipid phosphatase activity of PTEN is critical for stabilizing intercellular junctions and reverting invasiveness.

Kotelevets L, van Hengel J, Bruyneel E, Mareel M, van Roy F, Chastre E - J. Cell Biol. (2001)

Bottom Line: In contrast, overexpression of wild-type PTEN did not counteract Ras-induced invasiveness of MDCKras-f cells expressing low levels of E-cadherin.PTEN effects were not associated with marked changes in accumulation or phosphorylation levels of E-cadherin and associated catenins.Interestingly, PTEN effects were mimicked by N-cadherin-neutralizing antibody in the glioblastoma cell lines.

View Article: PubMed Central - PubMed

Affiliation: Institut National de la Santé et de la Recherche Médicale (INSERM) U410, Faculté de Médecine Bichat, 75018 Paris, France.

ABSTRACT
To analyze the implication of PTEN in the control of tumor cell invasiveness, the canine kidney epithelial cell lines MDCKras-f and MDCKts-src, expressing activated Ras and a temperature-sensitive v-Src tyrosine kinase, respectively, were transfected with PTEN expression vectors. Likewise, the human PTEN-defective glioblastoma cell lines U87MG and U373MG, the melanoma cell line FM-45, and the prostate carcinoma cell line PC-3 were transfected. We demonstrate that ectopic expression of wild-type PTEN in MDCKts-src cells, but not expression of PTEN mutants deficient in either the lipid or both the lipid and protein phosphatase activities, reverted the morphological transformation, induced cell-cell aggregation, and suppressed the invasive phenotype in an E-cadherin-dependent manner. In contrast, overexpression of wild-type PTEN did not counteract Ras-induced invasiveness of MDCKras-f cells expressing low levels of E-cadherin. PTEN effects were not associated with marked changes in accumulation or phosphorylation levels of E-cadherin and associated catenins. Wild-type, but not mutant, PTEN also reverted the invasive phenotype of U87MG, U373MG, PC-3, and FM-45 cells. Interestingly, PTEN effects were mimicked by N-cadherin-neutralizing antibody in the glioblastoma cell lines. Our data confirm the differential activities of E- and N-cadherin on invasiveness and suggest that the lipid phosphatase activity of PTEN exerts a critical role in stabilizing junctional complexes and restraining invasiveness.

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Related in: MedlinePlus

Immunofluorescent staining of E-cadherin in parental MDCKts-src cells and their wild-type PTEN transfectants grown at 40°C or after switch to 35°C. E-cadherin is concentrated at cell–cell contacts at the nonpermissive temperature for Src activity. Note that it is more diffusely distributed over the surface of dissociated MDCKts-src cells at the permissive temperature but largely concentrated at sites of cell–cell contacts in MDCKts-srcPTENwt18 cells. Bar, 10 μm.
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fig3: Immunofluorescent staining of E-cadherin in parental MDCKts-src cells and their wild-type PTEN transfectants grown at 40°C or after switch to 35°C. E-cadherin is concentrated at cell–cell contacts at the nonpermissive temperature for Src activity. Note that it is more diffusely distributed over the surface of dissociated MDCKts-src cells at the permissive temperature but largely concentrated at sites of cell–cell contacts in MDCKts-srcPTENwt18 cells. Bar, 10 μm.

Mentions: We next compared the expression, phosphorylation level, and cellular localization of E-cadherin and associated proteins in MDCKts-src and MDCKts-srcPTENwt cells before and after a shift to the permissive temperature for Src activity. At the restrictive temperature, the E-cadherin signal was concentrated at cell–cell contacts (Fig. 3 A). Time-course studies showed that Src activation in MDCKts-src cells resulted in progressive reduction of junctional complexes, delocalization of E-cadherin from the cell surface, and loss of epithelioid morphotype (Fig. 3, B and C). In contrast, MDCKts-srcPTENwt cells preserved cell–cell junctions and E-cadherin localization for longer times (Fig. 3, D–F). The same was observed for α-catenin, β-catenin, and p120ctn (unpublished data).


The lipid phosphatase activity of PTEN is critical for stabilizing intercellular junctions and reverting invasiveness.

Kotelevets L, van Hengel J, Bruyneel E, Mareel M, van Roy F, Chastre E - J. Cell Biol. (2001)

Immunofluorescent staining of E-cadherin in parental MDCKts-src cells and their wild-type PTEN transfectants grown at 40°C or after switch to 35°C. E-cadherin is concentrated at cell–cell contacts at the nonpermissive temperature for Src activity. Note that it is more diffusely distributed over the surface of dissociated MDCKts-src cells at the permissive temperature but largely concentrated at sites of cell–cell contacts in MDCKts-srcPTENwt18 cells. Bar, 10 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2199329&req=5

fig3: Immunofluorescent staining of E-cadherin in parental MDCKts-src cells and their wild-type PTEN transfectants grown at 40°C or after switch to 35°C. E-cadherin is concentrated at cell–cell contacts at the nonpermissive temperature for Src activity. Note that it is more diffusely distributed over the surface of dissociated MDCKts-src cells at the permissive temperature but largely concentrated at sites of cell–cell contacts in MDCKts-srcPTENwt18 cells. Bar, 10 μm.
Mentions: We next compared the expression, phosphorylation level, and cellular localization of E-cadherin and associated proteins in MDCKts-src and MDCKts-srcPTENwt cells before and after a shift to the permissive temperature for Src activity. At the restrictive temperature, the E-cadherin signal was concentrated at cell–cell contacts (Fig. 3 A). Time-course studies showed that Src activation in MDCKts-src cells resulted in progressive reduction of junctional complexes, delocalization of E-cadherin from the cell surface, and loss of epithelioid morphotype (Fig. 3, B and C). In contrast, MDCKts-srcPTENwt cells preserved cell–cell junctions and E-cadherin localization for longer times (Fig. 3, D–F). The same was observed for α-catenin, β-catenin, and p120ctn (unpublished data).

Bottom Line: In contrast, overexpression of wild-type PTEN did not counteract Ras-induced invasiveness of MDCKras-f cells expressing low levels of E-cadherin.PTEN effects were not associated with marked changes in accumulation or phosphorylation levels of E-cadherin and associated catenins.Interestingly, PTEN effects were mimicked by N-cadherin-neutralizing antibody in the glioblastoma cell lines.

View Article: PubMed Central - PubMed

Affiliation: Institut National de la Santé et de la Recherche Médicale (INSERM) U410, Faculté de Médecine Bichat, 75018 Paris, France.

ABSTRACT
To analyze the implication of PTEN in the control of tumor cell invasiveness, the canine kidney epithelial cell lines MDCKras-f and MDCKts-src, expressing activated Ras and a temperature-sensitive v-Src tyrosine kinase, respectively, were transfected with PTEN expression vectors. Likewise, the human PTEN-defective glioblastoma cell lines U87MG and U373MG, the melanoma cell line FM-45, and the prostate carcinoma cell line PC-3 were transfected. We demonstrate that ectopic expression of wild-type PTEN in MDCKts-src cells, but not expression of PTEN mutants deficient in either the lipid or both the lipid and protein phosphatase activities, reverted the morphological transformation, induced cell-cell aggregation, and suppressed the invasive phenotype in an E-cadherin-dependent manner. In contrast, overexpression of wild-type PTEN did not counteract Ras-induced invasiveness of MDCKras-f cells expressing low levels of E-cadherin. PTEN effects were not associated with marked changes in accumulation or phosphorylation levels of E-cadherin and associated catenins. Wild-type, but not mutant, PTEN also reverted the invasive phenotype of U87MG, U373MG, PC-3, and FM-45 cells. Interestingly, PTEN effects were mimicked by N-cadherin-neutralizing antibody in the glioblastoma cell lines. Our data confirm the differential activities of E- and N-cadherin on invasiveness and suggest that the lipid phosphatase activity of PTEN exerts a critical role in stabilizing junctional complexes and restraining invasiveness.

Show MeSH
Related in: MedlinePlus