Cytostatic Activity of Adenosine Triphosphate-Competitive Kinase Inhibitors in BRAF Mutant Thyroid Carcinoma Cells

• Published in: The journal of clinical endocrinology and metabolism 2010-01, Vol.95 (1), p.450-455
• Main Authors: Salerno, Paolo, De Falco, Valentina, Tamburrino, Anna, Nappi, Tito Claudio, Vecchio, Giancarlo, Schweppe, Rebecca E, Bollag, Gideon, Santoro, Massimo, Salvatore, Giuliana
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - antagonists & inhibitors; Adenosine Triphosphate - metabolism; Binding, Competitive - drug effects; Biological and medical sciences; Carcinoma - genetics; Carcinoma - pathology; Cell Proliferation - drug effects; Cytostatic Agents - pharmacology; Drug Evaluation, Preclinical; Endocrinopathies; Extracellular Signal-Regulated MAP Kinases - metabolism; Feeding. Feeding behavior; Fundamental and applied biological sciences. Psychology; Humans; Indoles - pharmacology; Malignant tumors; Medical sciences; Mutant Proteins - antagonists & inhibitors; Mutant Proteins - genetics; Phosphorylation - drug effects; Protein Kinase Inhibitors - pharmacology; Proto-Oncogene Proteins B-raf - antagonists & inhibitors; Proto-Oncogene Proteins B-raf - genetics; Serum - physiology; Sulfonamides - pharmacology; Thyroid Neoplasms - genetics; Thyroid Neoplasms - pathology; Thyroid. Thyroid axis (diseases); Tumor Cells, Cultured; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2009-0373

Context: The V600E mutation accounts for the vast majority of thyroid carcinoma-associated BRAF mutations. Objective: The aim was to study the effects of the two BRAF V600E ATP-competitive kinase inhibitors, PLX4032 and PLX4720, in thyroid carcinoma cell lines. Experimental Design: We examined the activity of PLX4032 and PLX4720 in thyroid carcinoma cell lines harboring BRAF V600E (8505C, BCPAP, SW1736, BHT101), NRAS Q61R (HTH7), KRAS G12R (CAL62), HRAS G13R (C643), or RET/PTC1 (TPC-1) oncogenes. Normal thyrocytes (PC Cl 3) were used as control. Results: Both compounds inhibited the proliferation of BRAF mutant cell lines, but not normal thyrocytes, with a half maximal effective concentration (EC50) ranging from 78–113 nm for PLX4720 and from 29–97 nm for PLX4032. Doses equal to or higher than 500 nm were required to achieve a similar effect in BRAF wild-type cancer cells. Phosphorylation of ERK 1/2 and MAPK kinase (MEK) 1/2 decreased upon PLX4032 and PLX4720 treatment in BRAF mutant thyroid carcinoma cells but not in normal thyroid cells or in cell lines harboring mutations of RAS or RET/PTC1 rearrangements. PLX4032 and PLX4720 treatment induced a G1 block and altered expression of genes involved in the control of G1-S cell-cycle transition. 8505C cell tumor xenografts were smaller in nude mice treated with PLX4032 than in control mice. This inhibition was associated with reduction of phospho-ERK and phospho-MEK levels. Conclusions: This study provides additional evidence of the promising nature of mutant BRAF as a molecular target for thyroid carcinoma cells. This in vitro study provides additional evidence of the promising nature of mutant BRAF as a molecular target for BRAF V600E-positive thyroid cancer.