mTOR pathway overactivation in BRAF mutated papillary thyroid carcinoma.
J Clin Endocrinol Metab
; 97(7): E1139-49, 2012 Jul.
Article
em En
| MEDLINE
| ID: mdl-22549934
ABSTRACT
CONTEXT There are several genetic and molecular evidences suggesting dysregulation of the mammalian target of rapamycin (mTOR) pathway in thyroid neoplasia. Activation of the phosphatidylinositol-3-kinase/AKT pathway by RET/PTC and mutant RAS has already been demonstrated, but no data have been reported for the BRAF(V600E) mutation. OBJECTIVE:
The aim of this study was to evaluate the activation pattern of the mTOR pathway in malignant thyroid lesions and whether it may be correlated with known genetic alterations, as well as to explore the mechanisms underlying mTOR pathway activation in these neoplasias.RESULTS:
We observed, by immunohistochemical evaluation, an up-regulation/activation of the mTOR pathway proteins in thyroid cancer, particularly in conventional papillary thyroid carcinoma (cPTC). Overactivation of the mTOR signaling was particularly evident in cPTC samples harboring the BRAF(V600E) mutation. Transfection assays with BRAF expression vectors as well as BRAF knockdown by small interfering RNA revealed a positive association between BRAF expression and mTOR pathway activation, which appears to be mediated by pLKB1 Ser428, and emerged as a possible mechanism contributing to the association between BRAF mutation and mTOR pathway up-regulation. When we evaluated the rapamycin in the growth of thyroid cancer cell lines, we detected that cell lines with activating mutations in the MAPK pathway show a higher sensitivity to this drug.CONCLUSIONS:
We determined that the AKT/mTOR pathway is particularly overactivated in human cPTC harboring the BRAF(V600E) mutation. Moreover, our results suggest that the mTOR pathway could be a good target to enhance therapy effects in certain types of thyroid carcinoma, namely in those harboring the BRAF(V600E) mutation.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Neoplasias da Glândula Tireoide
/
Mutação de Sentido Incorreto
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Proteínas Proto-Oncogênicas B-raf
/
Serina-Treonina Quinases TOR
Limite:
Humans
Idioma:
En
Revista:
J Clin Endocrinol Metab
Ano de publicação:
2012
Tipo de documento:
Article
País de afiliação:
Portugal