Combined antitumor activity of cucurbitacin B and docetaxel in laryngeal cancer

Combination therapy with multiple drugs is a common practice in the treatment of cancer. The promising clinical activity of docetaxel has promoted considerable interest in combining it with other antitumor agents. To determine whether cucurbitacin B can enhance chemosensitivity, to docetaxel in laryngeal cancer, in the present study, we investigated the combined antitumor effect of cucurbitacin B with docetaxel on Hep-2, a human laryngeal cancer cell line. We treated Hep-2 cells with cucurbitacin B alone or in combination with docetaxel and evaluated cell growth, cell cycle distribution, and apoptosis using MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide) assay, flow cytometry, and fluorescent microscopy. Our results showed that, in comparison with single agent treatment, the combination of cucurbitacin B and docetaxel produced greater efficacy in growth inhibition, cell cycle arrest at G(2)/M phase, and apoptosis induction. Measuring the modulation of regulators in the cell cycle, apoptosis and signal transductions by Western blot analysis showed that the combination effect of cucurbitacin B and docetaxel was due to suppress the expression of p-STAT3 (signal transducers and activators of transcription 3), Bcl-2, and cyclin B1. Moreover, our in vivo studies were reproduced in a mouse xenograft model, where, the combination of cucurbitacin B with docetaxel synergestively inhibited tumor growth. Together, this investigation suggests that cucurbitacin B combined with docetaxel may be a feasible strategy to enhance the effects of chemotherapy in patients with laryngeal cancer. (c) 2008 Elsevier B.V. All rights reserved.