TY - JOUR
T1 - RAI(ShcC/N-Shc)-dependent recruitment of GAB1 to RET oncoproteins potentiates PI3-K signalling in thyroid tumors
AU - De Falco, Valentina
AU - Guarino, Valentina
AU - Malorni, Luca
AU - Cirafici, Anna Maria
AU - Troglio, Flavia
AU - Erreni, Marco
AU - Pelicci, Giuliana
AU - Santoro, Massimo
AU - Melillo, Rosa Marina
N1 - Funding Information:
We thank Francesco Curcio for P5 cells, JM Hershman for BHP cells, and S Giord ano and P Gual for GAB1 plasmid s. We are also grateful to Fulvio Basolo, who provided us the human tumor samples. This work was supported by the Associazione Italiana per la Ricerca sul Cancro (AIRC), by the Ministero Italiano per l’Universita’, Istruzione e Ricerca Scientifica (MIUR), by the BIOGEM s.c.a.r.l. (Biologia e Genetica Molecolare nel Mezzogiorno d’Italia) and by the Centro Regionale di Competenza GEAR (Genomic for Applied Research). VG was a fellow of the Centro Regionale di Competenza GEAR.
PY - 2005/9/15
Y1 - 2005/9/15
N2 - RAI, also named ShcC/N-Shc, one of the members of the Shc proteins family, is a substrate of the RET receptor tyrosine kinase. Here, we show that RAI forms a protein complex with both RET/MEN2A and RET/PTC oncoproteins. By coimmunoprecipitation, we found that RAI associates with the Grb2-associated binder1 (GAB1) adapter. This association is constitutive, but, in the presence of RET oncoproteins, both RAI and GAB1 are tyrosine-phosphorylated, and the stoichiometry of this interaction remarkably increases. Consequently, the p85 regulatory subunit of phosphatidylinositol-3 kinase (PI-3K) is recruited to the complex, and its downstream effector Akt is activated. We show that human thyroid cancer cell lines derived from papillary or medullary thyroid carcinoma (PTC or MTC) carrying, respectively, RET/PTC and RET/MEN2A oncoproteins express RAI proteins. We also show that human PTC samples express higher levels of RAI, when compared to normal thyroid tissue. In thyroid cells expressing RET/PTC1, ectopic expression of RAI protects cells from apoptosis; on the other hand, the silencing of endogenous RAI by small inhibitory duplex RNAs in a PTC cell line that expresses endogenous RET/PTC1, increases the rate of spontaneous apoptosis. These data suggest that RAI is a critical substrate for RET oncoproteins in thyroid carcinomas.
AB - RAI, also named ShcC/N-Shc, one of the members of the Shc proteins family, is a substrate of the RET receptor tyrosine kinase. Here, we show that RAI forms a protein complex with both RET/MEN2A and RET/PTC oncoproteins. By coimmunoprecipitation, we found that RAI associates with the Grb2-associated binder1 (GAB1) adapter. This association is constitutive, but, in the presence of RET oncoproteins, both RAI and GAB1 are tyrosine-phosphorylated, and the stoichiometry of this interaction remarkably increases. Consequently, the p85 regulatory subunit of phosphatidylinositol-3 kinase (PI-3K) is recruited to the complex, and its downstream effector Akt is activated. We show that human thyroid cancer cell lines derived from papillary or medullary thyroid carcinoma (PTC or MTC) carrying, respectively, RET/PTC and RET/MEN2A oncoproteins express RAI proteins. We also show that human PTC samples express higher levels of RAI, when compared to normal thyroid tissue. In thyroid cells expressing RET/PTC1, ectopic expression of RAI protects cells from apoptosis; on the other hand, the silencing of endogenous RAI by small inhibitory duplex RNAs in a PTC cell line that expresses endogenous RET/PTC1, increases the rate of spontaneous apoptosis. These data suggest that RAI is a critical substrate for RET oncoproteins in thyroid carcinomas.
KW - RAI and GAB1 adaptors
KW - RET oncogenes
KW - Thyroid tumor
UR - http://www.scopus.com/inward/record.url?scp=30544439694&partnerID=8YFLogxK
U2 - 10.1038/sj.onc.1208776
DO - 10.1038/sj.onc.1208776
M3 - Article
SN - 0950-9232
VL - 24
SP - 6303
EP - 6313
JO - Oncogene
JF - Oncogene
IS - 41
ER -
