Pleiotropic Effects of Fenbendazole in Human NSCLC
Fenben is a benzimidazole with antihelmintic activity and antineoplastic properties. Due to its multitargeted nature, fenben is expected to have multiple cell killing mechanisms and circumvent the development of resistance to single-target drugs. Unlike most anticancer agents, which induce apoptosis through destabilization of microtubules, fenben also inhibits glucose uptake, impairing glycolysis and lowering lactate levels in culture supernatants. These pleiotropic effects may be of major importance in cancer therapy.
We investigated the effects of 2- and 24-h fenbendazole treatments on cell viability using a colony formation assay. Treatments were performed in the presence or absence of severe hypoxia (2% oxygen). The survival curves showed that fenbendazole was not toxic to aerobic EMT6 cells even at drug concentrations approaching the limit of solubility, but it did have significant effects on cell clonogenicity. Interestingly, the yield-corrected surviving fractions were significantly lower for 24-h treated cells.
Since inhibition of tubulin polymerization is a critical step in mitotic catastrophe, we investigated whether fenbendazole also affects the progression through metaphase. A549 cells were serum synchronized, and treatment with different doses of FZ was initiated at the time point indicated on the y-axis. At the times when cell cycle arrest was observed, cyclin B1 levels were measured in cell extracts.
Interestingly, we found that FZ caused an early increase of cyclin B1/CDK1 levels (Fig. 1a). Since acetylation of tubulin is a key feature for its microtubule stabilization, we tested the effect of FZ on acetylation status in human NSCLC cells. The results showed that, unlike nocodazole, taxol and colchicine which all cause a reduction in the amount of acetylated tubulin, FZ only slightly reduced the level of acetylated tubulin. fenben