Differential regulation of components of the focal adhesion complex by heregulin: role of phosphatase SHP-2.
Heregulin (HRG) has been implicated in the progression of breast cancer cells to a malignant phenotype, a process that involves changes in cell motility and adhesion. Here we demonstrate that HRG differentially regulates the site-specific phosphorylation of the focal adhesion components focal adhesion kinase (FAK) and paxilin in a dose-dependent manner. HRG at suboptimal doses (0.01 and 0.1 nM) increased adhesion of cells to the substratum, induced phosphorylation of FAK at Tyr-577, -925, and induced formation of well-defined focal points in breast cancer cell line MCF-7. HRG at a dose of 1 nM, increased migratory potential of breast cancer cells, selectively dephosphorylated FAK at Tyr-577, -925, and paxillin at Tyr-31. Tyrosine phosphorylation of FAK at Tyr-397 remained unaffected by HRG stimulation. FAK associated with HER2 only in response to 0.01 nM HRG. In contrast, 1 nM HRG induced activation and increased association of tyrosine phosphatase SHP-2 with HER2 but decreased association of HER2 with FAK. Expression of dominant-negative SHP-2 blocked HRG-mediated dephosphorylation of FAK and paxillin, leading to persistent accumulation of mature focal points. Our results suggest that HRG differentially regulates signaling from focal adhesion complexes through selective phosphorylation and dephosphorylation and that tyrosine phosphatase SHP-2 has a role in the HRG signaling.
Vadlamudi
Ratna K
RK
Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA. rvadlamudi@mdanderson.org
Adam
Liana
L
Nguyen
Diep
D
Santos
Manes
M
Kumar
Rakesh
R
D003598:Cytoskeletal Proteins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D005799:Genes, Dominant; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D020890:Neuregulin-1 / Q000494:pharmacology*; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D013379:Substrate Specificity; D014407:Tumor Cells, Cultured
D003598:Cytoskeletal Proteins; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D047908:Intracellular Signaling Peptides and Proteins; D020890:Neuregulin-1; D051419:Paxillin; D010750:Phosphoproteins; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; D011505:Protein-Tyrosine Kinases; D018719:Erb-b2 Receptor Tyrosine Kinases; C496061:PXN protein, human; C496050:PTK2 protein, human; C516724:PTPN11 protein, human; C509249:PTPN6 protein, human