Head and neck squamous cell carcinoma is highly sensitive to vinorelbine in Vitro

The vinorelbine sensitivity of eight recently established head and neck squamous cell carcinoma (SCC) cell lines was tested using the 96-well plate clonogenic assay. The chemosensitivity of these head and neck SCC cell lines to vinorelbine expressed as IC50, corresponding to the drug concentration causing 50% inhibition in clonogenic survival, varied between 0.6 and 1.0 nM. The dose-dependent growth inhibition caused by vinorelbine was measured in three of these cell lines. A clear growth inhibition was observed at a concentration of 3 nM. The same cell lines were studied with flow cytometry. When exposed to 3 nM and 5 nM vinorelbine, an accumulation of the cells in the G2/M-phase was observed in all cultures after 12 hours. The morphological changes induced by 3 nM and 5 nM vinorelbine to the UT-SCC-33 cell line were analysed with time-lapse video microscopy. In the cultures treated with 5 nM vinorelbine, the cells stayed mitotically arrested for 2-32 hours and thereafter died morphologically by apoptosis. These results indicate that, in vitro, the head and neck SCC is consistently sensitive to vinorelbine, which blocks the cell cycle in G2/M, the most radiosensitive phase. These encouraging results suggest that vinorelbine may potentially be used in conjunction with radiotherapy in the treatment of head and neck SCC.