Identification of the product of two oncogenic rearranged forms of the RET proto-oncogene in papillary thyroid carcinomas.
In papillary thyroid carcinomas, we have identified two tumor-specific rearrangements of the RET proto-oncogene leading to the formation of different transforming fusion products sharing the tyrosine kinase (tk) domain of the proto-oncogene and designated ptc-1 and ptc-2. We have analysed ptc-1 and ptc-2 products by immunoprecipitation with specific anti-RET antibodies followed by immunoblotting with the same reagent or with antibodies specific for phosphotyrosine (P-tyr) residues. The anti-RET antibodies were reactive with 64-kDa (p64ptc-1) and 81-kDa (p81ptc-2) proteins from lysates of ptc-1 and ptc-2 transformed cells, respectively, and identified two proteins of 140 kDa and 160 kDa from extracts of SK-N-SH, a neuroblastoma cell line previously shown to express two differently glycosylated forms of the normal RET product. The anti P-tyr antibodies, while detecting the same p64ptc-1 and p81ptc-2 proteins from ptc-1 and ptc-2 extracts, did not show any specific band in the neuroblastoma lysates. An additional set of experiments led us to conclude that, whereas the normal product of the RET proto-oncogene is a membrane-associated receptor-like molecule not intrinsically phosphorylated on tyrosine, both oncogenic forms of RET, ptc-1 and ptc-2, are constitutively phosphorylated on tyrosine, display an 'in vitro' autophosphorylation activity, are translocated from the membrane to the cytoplasm and are apparently unaffected by protein kinase C modulation.
Lanzi
C
C
Divisione di Oncologia Sperimentale B, Istituto Nazionale Tumori, Milan, Italy.
Borrello
M G
MG
Bongarzone
I
I
Migliazza
A
A
Fusco
A
A
Grieco
M
M
Santoro
M
M
Gambetta
R A
RA
Zunino
F
F
Della Porta
G
G
D016475:3T3 Cells; D000818:Animals; D015153:Blotting, Western; D002291:Carcinoma, Papillary / Q000737:chemistry / Q000235:genetics*; D029721:Drosophila Proteins; D015321:Gene Rearrangement; D006801:Humans; D051379:Mice; D010766:Phosphorylation; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000032:analysis*; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000032:analysis* / Q000235:genetics; D051096:Proto-Oncogene Proteins c-ret; D011519:Proto-Oncogenes; D020794:Receptor Protein-Tyrosine Kinases; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013964:Thyroid Neoplasms / Q000737:chemistry / Q000235:genetics*; D014443:Tyrosine / Q000378:metabolism
D029721:Drosophila Proteins; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases; C416649:Ret protein, Drosophila; C494999:Ret protein, mouse; D013755:Tetradecanoylphorbol Acetate