title: Src-mediated phosphorylation of the tyrosine phosphatase PRL-3 is required for PRL-3 promotion of Rho activation, motility and invasion.
abstract: The metastasis-associated tyrosine phosphatase PRL-3/PTP4A is upregulated in numerous cancers, but the mechanisms modulating PRL-3 activity other than its expression levels have not been investigated. Here we report evidence for both Src-dependent tyrosine phosphorylation of PRL-3 and Src-mediated regulation of PRL-3 biological activities. We used structural mutants, pharmacological inhibitors and siRNA to demonstrate Src-dependent phosphorylation of endogenous PRL-3 in SW480 colon cancer cells. We also demonstrated that PRL-3 was not tyrosine phosphorylated in SYF mouse embryo fibroblasts deficient in Src, Yes and Fyn unless Src was re-expressed. Further, we show that platelet-derived growth factor (PDGF) can stimulate PRL-3 phosphorylation in a Src-dependent manner. Finally, we show that PRL-3-induced cell motility, Matrigel invasion and activation of the cytoskeleton-regulating small GTPase RhoC were abrogated in the presence of the phosphodeficient PRL-3 mutant Y53F, or by use of a Src inhibitor. Thus, PRL-3 requires the activity of a Src kinase, likely Src itself, to promote these cancer-associated phenotypes. Our data establish a model for the regulation of PRL-3 by Src that supports the possibility of their coordinate roles in signaling pathways promoting invasion and metastasis, and supports simultaneous use of novel molecularly targeted therapeutics directed at these proteins.
authors.affiliation: Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America.
authors.forename: James J
authors.initials: JJ
authors.lastname: Fiordalisi
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Dewar
authors.forename: Lee M
authors.initials: LM
authors.lastname: Graves
authors.forename: James P
authors.initials: JP
authors.lastname: Madigan
authors.forename: Adrienne D
authors.initials: AD
authors.lastname: Cox
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D003094:Collagen; D004338:Drug Combinations; D006801:Humans; D017874:Immediate-Early Proteins / Q000378:metabolism*; D047468:Immunoprecipitation; D007797:Laminin; D051379:Mice; D008954:Models, Biological; D009361:Neoplasm Invasiveness / Q000503:physiopathology; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000378:metabolism*; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D011509:Proteoglycans; D034741:RNA, Small Interfering; D018631:ras Proteins / Q000378:metabolism; D000075024:rhoC GTP-Binding Protein; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D004338:Drug Combinations; D017874:Immediate-Early Proteins; D007797:Laminin; D010982:Platelet-Derived Growth Factor; D011509:Proteoglycans; C111534:Ptp4a3 protein, mouse; D034741:RNA, Small Interfering; C059485:matrigel; D003094:Collagen; D019061:src-Family Kinases; D017027:Protein Tyrosine Phosphatases; C512911:Rhoc protein, mouse; D018631:ras Proteins; D000075024:rhoC GTP-Binding Protein