The kinesin Eg5 inhibitor K858 induces apoptosis and reverses the malignant invasive phenotype in human glioblastoma cells

Glioblastoma multiforme is the most common primary malignant brain tumor and its current chemotherapeutic options are limited to temozolomide. Recently, some synthetic compounds acting as inhibitors of kinesin spindle protein Eg5 have shown pronounced antitumor activity. Our group has recently demonstrated that one of these kinesin Eg5 inhibitors, named K858, exerted important antiproliferative and apoptotic effects on breast cancer cells. Since glioblastoma cells usually express high levels of kinesin Eg5, we tested the effect of K858 on two human glioblastoma cell lines (U-251 and U-87) and found that K858 inhibited cell growth, induced apoptosis, reversed epithelial-mesenchymal transition and inhibited migration in both cell lines. We also detected that, at the same time, K858 increased the expression of survivin, an anti-apoptotic molecule, and that the forced down-regulation of survivin, obtained with the specific inhibitor YM155, boosted K858-dependent apoptosis. This indicated that the anti-tumor activity of K858 on glioblastoma cells is limited by the over-expression of survivin and that the negative regulation of this protein sensitizes tumor cells to K858. These data confirmed that kinesin Eg5 is an interesting target for new therapeutic approaches for glioblastoma. We showed that K858, specifically, was a potent inhibitor of replication, an inducer of apoptosis and a negative regulator of the invasive phenotype for glioblastoma cells.