c-Cbl is a suppressor of the neu oncogene.
A rodent oncogenic mutant of the Neu receptor tyrosine kinase is a useful experimental model because overexpression of the respective receptor, namely HER2/ErbB-2, in human malignancies is associated with relatively aggressive diseases. Here we show that the oncogenic form of Neu is constitutively associated with the product of the c-cbl proto-oncogene and is part of a large complex that includes the phosphoinositide 3-kinase and Shc. Ectopic expression of c-Cbl, a ubiquitin-protein isopeptide ligase specific to activated tyrosine kinases, causes rapid removal of Neu from the cell surface and severely reduces signaling downstream of oncogenic Neu. c-Cbl-induced down-regulation of Neu involves covalent attachment of ubiquitin molecules and requires the carboxyl-terminal domain of Neu. The negative effect of c-Cbl is antagonized by v-Cbl, a virus-encoded oncogenic truncated form of c-Cbl. In an in vivo model, infection of a Neu-transformed neuroblastoma with a c-Cbl-encoding retrovirus caused enhanced down-regulation of Neu and correlated with tumor retardation. Our results implicate c-Cbl in negative regulation of Neu and offer a potential target for treatment of HER2/ErbB-2-positive human malignancies.
Levkowitz
G
G
Departments of Biological Regulation and Immunology, The Weizmann Institute of Science, Rehovot 76100, Israel.
Oved
S
S
Klapper
L N
LN
Harari
D
D
Lavi
S
S
Sela
M
M
Yarden
Y
Y
D016475:3T3 Cells; D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D019921:Biotinylation; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D015536:Down-Regulation; D004591:Electrophoresis, Polyacrylamide Gel; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D008025:Ligases / Q000378:metabolism; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009447:Neuroblastoma / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D011233:Precipitin Tests; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D050721:Proto-Oncogene Proteins c-cbl; D051381:Rats; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D012190:Retroviridae / Q000235:genetics; D026362:Serum Response Factor; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D013997:Time Factors; D014162:Transfection; D044767:Ubiquitin-Protein Ligases
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000911:Antibodies, Monoclonal; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D008025:Ligases; D009687:Nuclear Proteins; D019869:Phosphatidylinositol 3-Kinases; D011506:Proteins; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D050721:Proto-Oncogene Proteins c-cbl; D018719:Erb-b2 Receptor Tyrosine Kinases; D026362:Serum Response Factor; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D044767:Ubiquitin-Protein Ligases; C000715470:MAS1 protein, human; C528024:SHC1 protein, human; C528034:Shc1 protein, mouse; C528035:Shc1 protein, rat; C067419:CBL protein, human; C493849:Cbl protein, mouse