The dual Aurora kinase inhibitor ZM447439 prevents anaplastic thyroid cancer cell growth and tumorigenicity

The anaplastic thyroid cancer (ATC) is among the most aggressive human tumors which fail to respond to all the currently available therapeutic approaches. As a consequence most patients die within a few months from diagnosis. In the present preclinical study, the effects of the ZM447439, a functional inhibitor of Aurora kinases, on the growth and tumorigenicity of a panel of ATC derived cell lines (CAL62, 8305C, 8505C and BHT-101) were evaluated. The treatment of the different ATC cells with ZM447439 inhibited proliferation in a time- and dose-dependent manner, with IC50 comprised between 0.5 mM and 5 mM. Moreover, the drug remarkably impaired the formation of colonies in soft agar of all the cell lines. Consistently with Aurora inhibition, immunoffuorescence and immunoblotting experiments demonstrated that Aurora auto-phosphorylation following drug treatment was completely abrogated, and treated cells were characterized by the presence of multiple spindles with short microtubules. In the same experiments we observed the loss of histone 113 phosphorylation on Ser10, specifically due to Aurora-B, after ZM447439 treatment. Time-lapse videomicroscopy and flow cytometric analysis demonstrated that in presence of ZM447439 the cells were able to enter mitosis but not to complete it, becoming polyploid. Almost all the ATC cell lines studied showed increased apoptosis after only 48 h of treatment. In conclusion, our data demonstrate that ZM447439 is effective in reducing cell growth and tumorigenicity of different ATC derived cell lines, and further investigations are needed to exploit its potential therapeutic value for ATC treatment.