title: c-Cbl-dependent EphA2 protein degradation is induced by ligand binding.
abstract: The EphA2 receptor protein tyrosine kinase is overexpressed and functionally altered in a large number of human carcinomas. Despite its elevated levels in cancer, the EphA2 on the surface of malignant cells demonstrates lower levels of ligand binding and tyrosine phosphorylation than the EphA2 on non-transformed epithelial cells. In our present study, we demonstrate that ligand-mediated stimulation causes EphA2 to be internalized and degraded. The mechanism of this response involves ligand-mediated autophosphorylation of EphA2, which promotes an association between EphA2 and the c-Cbl adaptor protein. We also show that c-Cbl promotes stimulation-dependent EphA2 degradation. These findings are important for understanding the causes of EphA2 overexpression in malignant cells and provide a foundation for investigating EphA2 as a potential target for therapeutic intervention.
authors.affiliation: Department of Basic Medical Sciences and Medicinal Chemistry and Molecular Pharmacology, Purdue University Cancer Center, West Lafayette, IN, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Walker-Daniels
authors.forename: David J
authors.initials: DJ
authors.lastname: Riese
authors.forename: Michael S
authors.initials: MS
authors.lastname: Kinch
mesh_terms: D000911:Antibodies, Monoclonal / Q000378:metabolism / Q000494:pharmacology / Q000648:ultrastructure; D001943:Breast Neoplasms / Q000201:enzymology* / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000473:pathology; D011992:Endosomes / Q000378:metabolism / Q000648:ultrastructure; D036382:Ephrin-A1 / Q000378:metabolism / Q000494:pharmacology / Q000648:ultrastructure; D004847:Epithelial Cells / Q000201:enzymology* / Q000473:pathology; D006801:Humans; D008024:Ligands; D011518:Proto-Oncogene Proteins / Q000378:metabolism* / Q000648:ultrastructure; D050721:Proto-Oncogene Proteins c-cbl; D036104:Receptor, EphA2 / Q000378:metabolism* / Q000648:ultrastructure; D011993:Recombinant Fusion Proteins / Q000378:metabolism / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D044767:Ubiquitin-Protein Ligases
chemical_list: D000911:Antibodies, Monoclonal; D036382:Ephrin-A1; D008024:Ligands; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D036104:Receptor, EphA2; C067419:CBL protein, human