CYTOTOXIC AND GENOTOXIC EFFECTS OF PACLITAXEL (TAXOL(R)) AND RADIATION IN A SQUAMOUS-CELL CARCINOMA CELL-LINE OF THE LARYNX

Paclitaxel (Taxol(R)) is an antimicrotubular agent which blocks the ce lls in the G2/M phase of the cell cycle. Because of this mechanism it is presumed that this drug could function as a radiation sensitizer. T he cytotoxic and genotoxic effects of paclitaxel and a combination of paclitaxel and radiation were studied in the human laryngeal carcinoma cell line HLac 79. The growth of the cells was significantly reduced at concentrations of paclitaxel as low as 10 nM. Flow cytometry data s howed a G2/M block after exposure to paclitaxel. Radiation at 12 and 2 4 h after drug treatment exerted an additive but no radiation sensitiz ing effect. As genotoxic effect paclitaxel induced multinucleated cell s, possibly in a synergistic manner, at low concentrations (10 nM) and radiation doses up to 3 Gy.