Inhibition of transforming activity of the ret/ptc1 oncoprotein by a 2-indolinone derivative.
ret-derived oncogenes are frequently and specifically expressed in thyroid tumors. In contrast to the ret receptor, ret oncoproteins are characterized by ligand-independent tyrosine-kinase activity and tyrosine phosphorylation. In this study, novel synthetic arylidene 2-indolinone compounds were evaluated as inhibitors of the ret/ptc1 tyrosine kinase. Four compounds inhibited ret/ptc1 activity in immunokinase assay (IC50 27-42 microM) including one (1,3-dihydro-5,6-dimethoxy-3-[(4-hydroxyphenyl) methylene)-2H-indol-2-one) (Cpd 1) that selectively inhibited the anchorage-independent growth of NIH3T3 transformants expressing the ret/ptc1 gene (NIH3T3ptc1 cells). Following exposure to Cpd 1, the transformed phenotype of NIH3T3ptc1 cells was reverted, within 24 hr, to a normal fibroblast-like morphology in adherent-cell culture. In these cells, the constitutive tyrosine phosphorylation of ret/ptc1, of the transducing adaptor protein shc and of a series of co-immunoprecipitated peptides became much reduced, as demonstrated by immunoprecipitation/Western-blot analyses. Data presented provide additional evidence that ret/ptc1 is directly implicated in malignant transformation, and demonstrate the ability of Cpd 1 to interfere in the signal transduction pathway constitutively activated by the ret/ptc1 oncoprotein. These results confirm the interest of the arylidene 2-indolinone class of tyrosine-kinase inhibitors as tools for the study of ret signaling and the control of cell proliferation in ret- and ret/ptcs-associated diseases.
Lanzi
C
C
Division of Experimental Oncology B, Istituto Nazionale Tumori, Milan, Italy. Lanzi@istitutotumori.mi.it
Cassinelli
G
G
Pensa
T
T
Cassinis
M
M
Gambetta
R A
RA
Borrello
M G
MG
Menta
E
E
Pierotti
M A
MA
Zunino
F
F
D000818:Animals; D015153:Blotting, Western; D002294:Carcinoma, Squamous Cell / Q000201:enzymology / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000378:metabolism*; D011905:Genes, ras; D006801:Humans; D007211:Indoles / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D015514:Oncogene Proteins, Fusion / Q000378:metabolism*; D000078183:Oxindoles; D010641:Phenotype; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D015398:Signal Transduction; D013964:Thyroid Neoplasms / Q000201:enzymology / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000201:enzymology / Q000378:metabolism*
C404643:1,3-dihydro-5,6-dimethoxy-3-((4-hydroxyphenyl)methylene)-2H-indol-2-one; D004791:Enzyme Inhibitors; D007211:Indoles; D015514:Oncogene Proteins, Fusion; D000078183:Oxindoles; C022960:2-oxindole; D011505:Protein-Tyrosine Kinases; C093573:ret-PTC fusion oncoproteins, human