title: Genetic deletion of the Pten tumor suppressor gene promotes cell motility by activation of Rac1 and Cdc42 GTPases.
abstract: Pten (Phosphatase and tensin homolog deleted on chromosome 10) is a recently identified tumor suppressor gene which is deleted or mutated in a variety of primary human cancers and in three cancer predisposition syndromes [1]. Pten regulates apoptosis and cell cycle progression through its phosphatase activity on phosphatidylinositol (PI) 3,4,5-trisphosphate (PI(3,4,5)P(3)), a product of PI 3-kinase [2-5]. Pten has also been implicated in controlling cell migration [6], but the exact mechanism is not very clear. Using the isogenic Pten(+/+) and Pten(-/-) mouse fibroblast lines, here we show that Pten deficiency led to increased cell motility. Reintroducing the wild-type Pten, but not the catalytically inactive Pten C124S or lipid-phosphatase-deficient Pten G129E mutant, reduced the enhanced cell motility of Pten-deficient cells. Moreover, phosphorylation of the focal adhesion kinase p125(FAK) was not changed in Pten(-/-) cells. Instead, significant increases in the endogenous activities of Rac1 and Cdc42, two small GTPases involved in regulating the actin cytoskeleton [7], were observed in Pten(-/-) cells. Overexpression of dominant-negative mutant forms of Rac1 and Cdc42 reversed the cell migration phenotype of Pten(-/-) cells. Thus, our studies suggest that Pten negatively controls cell motility through its lipid phosphatase activity by down-regulating Rac1 and Cdc42.
authors.affiliation: Department of Microbiology and Molecular Immunology, Howard Hughes Medical Institute, University of California at Los Angeles School of Medicine, Los Angeles, 90095-1735, USA.
authors.forename: J
authors.initials: J
authors.lastname: Liliental
authors.forename: S Y
authors.initials: SY
authors.lastname: Moon
authors.forename: R
authors.initials: R
authors.lastname: Lesche
authors.forename: R
authors.initials: R
authors.lastname: Mamillapalli
authors.forename: D
authors.initials: D
authors.lastname: Li
authors.forename: Y
authors.initials: Y
authors.lastname: Zheng
authors.forename: H
authors.initials: H
authors.lastname: Sun
authors.forename: H
authors.initials: H
authors.lastname: Wu
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000502:physiology*; D004789:Enzyme Activation; D017353:Gene Deletion; D016147:Genes, Tumor Suppressor; D051379:Mice; D008817:Mice, Mutant Strains; D051059:PTEN Phosphohydrolase; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics*; D025521:Tumor Suppressor Proteins; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*
chemical_list: D025521:Tumor Suppressor Proteins; D010744:Phosphoric Monoester Hydrolases; D051059:PTEN Phosphohydrolase; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein