Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.11.18 (MAP)
 7,412 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We show that treatment of a panel of thyroid carcinoma cell lines naturally harboring the RET/PTC1 oncogene, with the RET kinase inhibitors PP1 and ZD6474, results in reversible G(1) arrest. This is accompanied by interruption of Shc and mitogen-activated protein kinase (MAPK) phosphorylation, reduced levels of G(1) cyclins, and increased levels of the cyclin-dependent kinase inhibitor p27Kip1 because of a reduced protein turnover. MAP/extracellular signal-regulated kinase 1/2 inhibition by U0126 caused G(1) cyclins down-regulation and p27Kip1 up-regulation as well. Forced expression of RET/PTC in normal thyroid follicular cells caused a MAPK- and proteasome-dependent down-regulation of p27Kip1. Reduction of p27Kip1 protein levels by antisense oligonucleotides abrogated the G(1) arrest induced by RET/PTC blockade. Therefore, in thyroid cancer, RET/PTC-mediated MAPK activation contributes to p27Kip1 deregulation. This pathway is implicated in cell cycle progression and in response to small molecule kinase inhibitors.
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PMID:Regulation of p27Kip1 protein levels contributes to mitogenic effects of the RET/PTC kinase in thyroid carcinoma cells. 1517 89

Mutations of genes coding effectors of signaling pathway RET/PTC-RAS-RAF-MEK-ERK, involved in cell growth and proliferation, are important in papillary thyroid cancer development. To earlier discovered mutations of RAS and RET/PTC genes, BRAF gene mutation has been recently added. Mutation of BRAF gene appears in various types of carcinomas, but most frequently in malignant melanomas (66%) and papillary thyroid cancer (average 44%). The BRAF gene protein product belongs to the serine-threonine kinase family and to the RAF proteins subfamily, among which it is the strongest activator of MAP kinases cascade. The most frequently mutation of BRAF gene is thymine to adenine transversion at nucleotide position 1796 (T1796A). This point mutation causes valine to glutamic acid substitution at residue 599 (V599E), that results in constitutive and oncogenic activation of BRAF kinase. The relation between mutations of BRAF, RAS and RET/PTC genes has not been found, although they together exist in two thirds of papillary thyroid cancers. BRAF(TI796A) oncogene appears in papillary thyroid cancer, whereas it has not been found in follicular thyroid cancer and benign thyroid adenomas. For this reason mutated BRAF gene could be specific molecular marker, with relatively high sensitivity in diagnostics of papillary thyroid cancer. In addition, BRAF gene has been demonstrated as a novel prognostic biomarker, which correlates with unfavorable clinicopathological factors, such as extrathyroidal invasion and distant metastasis.
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PMID:[BRAF gene mutation in thyroid cancer]. 1670 43

Activating mutations of GNAq protein in a hotspot at codon 209 have been recently described in uveal melanomas. Since these neoplasms share with thyroid carcinomas a high frequency of MAP kinase pathway-activating mutations, we hypothesized whether GNAq mutations could also play a role in the development of thyroid carcinomas. Additionally, activating mutations of another subtype of G protein (GNAS1) are frequently found in hyperfunctioning thyroid adenomas, making it plausible that GNAq-activating mutations could also be found in some of these nodules. To investigate thyroid papillary carcinomas and thyroid hyperfunctioning nodules for GNAq mutations in exon 5, codon 209, a total of 32 RET/PTC, BRAF, and RAS negative thyroid papillary carcinomas and 13 hyperfunctioning thyroid nodules were evaluated. No mutations were identified. Although plausible, GNAq mutations seem not to play an important role in the development of thyroid follicular neoplasms, either benign hyperfunctioning nodules or malignant papillary carcinomas. Our results are in accordance with the literature, in which no GNAq hotspot mutations were found in thyroid papillary carcinomas, as well as in an extensive panel of other tumors. The molecular basis for MAP-kinase pathway activation in RET-PTC/BRAF/RAS negative thyroid carcinomas remains to be determined.
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PMID:GNAq mutations are not identified in papillary thyroid carcinomas and hyperfunctioning thyroid nodules. 2071 30

Thyroid carcinomas are rare and heterogeneous diseases representing less than 1% of all malignancies. The majority of thyroid carcinomas are differentiated entities (papillary and folliculary carcinomas) and are characterized by good prognosis and good response to surgery and radioiodine therapy. Nevertheless, about 10% of differentiated carcinomas recur and become resistant to all therapies. Anaplastic and medullary cancers are rare subtypes of thyroid cancer not suitable for radioiodine therapy. A small percentage of differentiated and all the anaplastic and medullary thyroid carcinomas often recur after primary treatments and are no longer suitable for other therapies. In the last years, several advances have been made in the field of molecular biology and tumorigenesis mechanisms of thyroid carcinomas. Starting from these issues, the targeted therapy may be employed as a new option. The MAP-Kinase pathway has been found often dysregulated in thyroid carcinomas and several upstream signals have been recognized as responsible for this feature. RET/PTC mutations are often discovered both in papillary and in medullary carcinomas, while B-RAF mutation is typical of papillary and anaplastic histologies. Also mTOR disruptions and VEGFR pathway disruption are common features in all advanced thyroid cancers. Some angiogenesis inhibitors and a number of RET/PTC pathway blocking agents are yet present in the clinical armamentarium. Vandetanib, cabozatinib and sorafenib have reached clinical use. A number of other biological compounds have been tested in phase II and III trials. Understanding the biology of thyroid cancers may help us to design a well shaped targeted therapy.
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PMID:Targeted therapy: a new hope for thyroid carcinomas. 2546 39