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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

Effects of wild-type or mutant PTEN expression on the accumulation and phosphorylation levels of E-cadherin and associated proteins in MDCKts-src cells and derivatives. (A) Western blotting of E-cadherin, α-catenin, β-catenin, and p120ctn in total cell lysates at permissive and nonpermissive temperature for Src activity. (B) Cell lysates from MDCK, MDCKts-src, and their derivatives grown at 37°C, 40°C, or 35°C were immunoprecipitated with the E-cadherin–specific mAb DECMA-1. The tyrosine phosphorylated components of cadherin–catenin complexes were revealed using the PY20 mAb and the ECL system.
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fig4: Effects of wild-type or mutant PTEN expression on the accumulation and phosphorylation levels of E-cadherin and associated proteins in MDCKts-src cells and derivatives. (A) Western blotting of E-cadherin, α-catenin, β-catenin, and p120ctn in total cell lysates at permissive and nonpermissive temperature for Src activity. (B) Cell lysates from MDCK, MDCKts-src, and their derivatives grown at 37°C, 40°C, or 35°C were immunoprecipitated with the E-cadherin–specific mAb DECMA-1. The tyrosine phosphorylated components of cadherin–catenin complexes were revealed using the PY20 mAb and the ECL system.

Mentions: Because E-cadherin activity crucially depends on its association with several cytoplasmic proteins, we analyzed the total amount of E-cadherin, and associated α-catenin, β-catenin, and p120ctn. We found that any of these expression levels were similar at both nonpermissive and permissive temperatures and also not significantly altered by PTEN expression (Fig. 4 A). In addition, Src-induced tyrosine phosphorylation of E-cadherin and associated catenins was comparable in MDCKts-src cells and their PTEN derivatives (Fig. 4 B). Thus, in the presence of wild-type PTEN, Src-induced tyrosine phosphorylation of E-cadherin junctional complexes is not sufficient to promote the disruption of adherens junctions.


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)

Effects of wild-type or mutant PTEN expression on the accumulation and phosphorylation levels of E-cadherin and associated proteins in MDCKts-src cells and derivatives. (A) Western blotting of E-cadherin, α-catenin, β-catenin, and p120ctn in total cell lysates at permissive and nonpermissive temperature for Src activity. (B) Cell lysates from MDCK, MDCKts-src, and their derivatives grown at 37°C, 40°C, or 35°C were immunoprecipitated with the E-cadherin–specific mAb DECMA-1. The tyrosine phosphorylated components of cadherin–catenin complexes were revealed using the PY20 mAb and the ECL system.
© Copyright Policy
Related In: Results  -  Collection

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

fig4: Effects of wild-type or mutant PTEN expression on the accumulation and phosphorylation levels of E-cadherin and associated proteins in MDCKts-src cells and derivatives. (A) Western blotting of E-cadherin, α-catenin, β-catenin, and p120ctn in total cell lysates at permissive and nonpermissive temperature for Src activity. (B) Cell lysates from MDCK, MDCKts-src, and their derivatives grown at 37°C, 40°C, or 35°C were immunoprecipitated with the E-cadherin–specific mAb DECMA-1. The tyrosine phosphorylated components of cadherin–catenin complexes were revealed using the PY20 mAb and the ECL system.
Mentions: Because E-cadherin activity crucially depends on its association with several cytoplasmic proteins, we analyzed the total amount of E-cadherin, and associated α-catenin, β-catenin, and p120ctn. We found that any of these expression levels were similar at both nonpermissive and permissive temperatures and also not significantly altered by PTEN expression (Fig. 4 A). In addition, Src-induced tyrosine phosphorylation of E-cadherin and associated catenins was comparable in MDCKts-src cells and their PTEN derivatives (Fig. 4 B). Thus, in the presence of wild-type PTEN, Src-induced tyrosine phosphorylation of E-cadherin junctional complexes is not sufficient to promote the disruption of adherens junctions.

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