ANTINEOPLASTIC ACTIVITY OF PACLITAXEL ON EXPERIMENTAL SUPERFICIAL BLADDER-CANCER - IN-VIVO AND IN-VITRO STUDIES

The effects of intravesical administration of paclitaxel (taxol) in a bladder tumor model in mice, as well as the drug's in vitro activity o n the same tumor cells, have been studied. Two cell lines, derived fro m MBT-2 cells, were employed in these experiments. The T50 line (obtai ned by many passages in mice) was much more aggressive in vivo than th e T5 line. In vivo paclitaxel treatment for 3 days after T5 implantati on resulted in a considerable retardation of tumor growth, whereas und er the same conditions the T50 line was much less, although still sign ificantly, affected. When treatment was started 1 day after tumor impl antation, both tumor variants were affected by paclitaxel to the same extent. The in vitro experiments utilized the MiCK assay, which allows continuous recording of the kinetics of cell growth. These studies re vealed a 39.8% inhibition of cell growth by 2.10(-8)M paclitaxel in th e T50 line and a 30-fold increase in concentration had only a small ad ditional effect on the degree of inhibition. At 2.10(-8)M paclitaxel, growth of T5 was inhibited by 21.7%, which increased to 35.2% at 6.10( -7)M. The treated cells displayed bundles of microtubuli, as described for other paclitaxel-treated cells. (C) 1997 Wiley-Liss, Inc.