Sorafenib inhibits intracellular signaling pathways and induces cell cycle arrest and cell death in thyroid carcinoma cells irrespective of histological origin or BRAF mutational status

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.

The inhibition of FGF receptor 1 activity mediates sorafenib antiproliferative effects in human malignant pleural mesothelioma tumor-initiating cells

“…As far as the mechanisms of action in MPM TICs, sorafenib treatment for 24–48 h induces G1 cell cycle arrest, as also reported in NSCLC [49] or thyroid cancer cell lines [50]. Interestingly, in our experimental model, cell death was mostly observed after 72 h of treatment, indicating that sorafenib inhibition of MPM TIC proliferation precedes the activation of the apoptotic process.…”

Comprehensive Analysis of miRNome Alterations in Response to Sorafenib Treatment in Colorectal Cancer Cells

“…Second, we observed a growth-inhibitory effect and an arrest in the S-phase of the cell cycle as the mode of the cytotoxic action of sorafenib, which has been previously described in papillary thyroid carcinoma cell lines (BHT101, B-CPAP and TK1) and anaplastic cell lines (SW1736 and Hth7) [28]. Furthermore, in medulloblastoma, the effect of sorafenib in Daoy cells showed a decrease of cells in the G1-phase and an increase of cells arrested in the S-phase [29].…”

Effects of sorafenib and an adenylyl cyclase activator on <i>in vitro</i> growth of well-differentiated thyroid cancer cells

“…Forskolin decreased the expression level of the cell cycle modulator cyclin D1, while sorafenib decreased CDK4 and p-RB in the 3 examined cell lines. A previous report suggested that forskolin induces G1 phase arrest [14] although sorafenib affects the cell cycle differently depending on the cell lines [9]. We postulate that the cAMP pathway activated by forskolin directly inhibits progression through the G1 phase of the cell cycle, resulting in growth suppression of well-differentiated thyroid carcinoma cells.…”

“…proliferation and neovascularization by inhibiting both RTKs, such as RET, vascular endothelial growth factor (VEGF), and platelet-derived growth factor (PDGF), and their downstream signaling pathway, that is, the MAPK pathway [7][8][9][10][11]. Especially, sorafenib is a multikinase inhibitor that suppresses various types of RTKs and the following MAPK pathway [7,9].…”

“…Especially, sorafenib is a multikinase inhibitor that suppresses various types of RTKs and the following MAPK pathway [7,9].…”