Abstract
BackgroundPatients with dedifferentiated or anaplastic thyroid carcinomas currently lack appropriate treatment options. Kinase inhibitors are among the most promising new agents as alternative strategies. The BRAF- and multi-kinase inhibitor, sorafenib, has already shown antitumor effects in thyroid carcinoma patients in a phase III clinical trial. In this study we aim to better characterize molecular effects and efficacy of sorafenib against thyroid carcinoma cells with various histological origins and different BRAF mutational status. Analysis of different signaling pathways affected by sorafenib may contribute to assist a more specific therapy choice with fewer side effects. Twelve thyroid carcinoma cell lines derived from anaplastic, follicular and papillary thyroid carcinomas with wildtype or mutationally activated BRAF were treated with sorafenib. Growth inhibition, cell cycle arrest, cell death induction and inhibition of intracellular signaling pathways were then comprehensively analyzed.MethodsCell viability was analyzed by MTT assay, and the cell cycle was assessed by flow cytometry after propidium iodide staining. Cell death was assessed by lactate dehydrogenase liberation assays, caspase activity assays and subG1 peak determinations. Inhibition of intracellular pathways was analyzed in dot blot and western blot analyses.ResultsSorafenib inhibited proliferation of all thyroid carcinoma cell lines tested with IC50 values ranging between 1.85 and 4.2 μM. Cells derived from papillary carcinoma harboring the mutant BRAFV600E allele were slightly more sensitive to sorafenib than those harboring wildtype BRAF. Cell cycle analyses and caspase assays showed a sorafenib-dependent induction of apoptosis in all cell lines, whereas increased lactate dehydrogenase release suggested cell membrane disruption. Sorafenib treatment caused a rapid inhibition of various MAP kinases in addition to inhibiting AKT and receptor tyrosine kinases.ConclusionsSorafenib inhibited multiple intracellular signaling pathways in thyroid carcinoma cells, which resulted in cell cycle arrest and the initiation of apoptosis. Sorafenib was effective against all thyroid carcinoma cell lines regardless of their tumor subtype origin or BRAF status, confirming that sorafenib is therapeutically beneficial for patients with any subtype of dedifferentiated thyroid cancer. Inhibition of single intracellular targets of sorafenib in thyroid carcinoma cells may allow the development of more specific therapeutic intervention with less side effects.
Highlights
Patients with dedifferentiated or anaplastic thyroid carcinomas currently lack appropriate treatment options
Sorafenib inhibited proliferation of cell lines derived from all thyroid tumor subtypes irrespective of BRAF status To assess whether sorafenib has a selective effect on proliferation of cells with different histological and molecular thyroid carcinoma backgrounds, we treated 12 cell lines with different histological origins and BRAFV600E mutational status for 48 h with a range of sorafenib concentrations or vehicle and assessed proliferative activity
Sorafenib treatment decreased the number of viable cells in all 12 thyroid carcinoma cell lines analyzed, and efficiency of sorafenib did not span a large range, since IC50 values for all 12 cell lines were between 1.85 μM and 4.2 μM (Table 1)
Summary
Patients with dedifferentiated or anaplastic thyroid carcinomas currently lack appropriate treatment options. The BRAF- and multi-kinase inhibitor, sorafenib, has already shown antitumor effects in thyroid carcinoma patients in a phase III clinical trial. Anaplastic (undifferentiated) thyroid carcinomas are highly aggressive and lethal tumors that have completely lost the ability to take up iodine [7]. Beside their aggressive growth the loss of capacity to uptake iodine makes both dedifferentiated and anaplastic thyroid carcinomas difficult to treat, and confer the poor patient prognosis. Chemotherapeutic treatment proved to be largely ineffective against aggressive thyroid carcinomas [8] These inadequacies of current treatment protocols for dedifferentiated and anaplastic thyroid carcinomas strongly emphasize the urgent need to establish novel targeted treatment options
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
